Document problems/solutions for using owned collections with SQLite where partially generated composite keys are not supported

## File a bug

### Include your code

I have a `Comment` owned entity type:
````cs
public class Comment { // owned entity type
public Comment(string text) { Text = text; }
public string Text { get; private set; }
}

public class Post {
public Post(string content) { Content = content; }
public long Id { get; private set; }
public string Content { get; private set; }
public ICollection Comments { get; private set; } = new HashSet();
}
````

And `Post`'s configuration includes:
````cs
builder.OwnsMany(x => x.Comments, x => {
x.Property(y => y.Text).IsRequired();
});
````

The seeding code includes this:
````cs
var post = new Post("content");
post.Comments.Add(new Comment("comment1"));
post.Comments.Add(new Comment("comment2"));
await _context.AddAsync(post);
await _context.SaveChangesAsync(); // throws here
````

When I use the postgres provider, I can successfully create, seed and edit the database.

When I use the sqlite provider, I can successfully create the database, but when I try to seed it I get an exception. See below.

### Include stack traces

````
ERR | Microsoft.EntityFrameworkCore.Database.Command | Failed executing DbCommand (1ms) [Parameters=[@p6='?', @p7='?' (Size = 4)], CommandType='Text', CommandTimeout='30']
INSERT INTO "Comment" ("PostId", "Text")
VALUES (@p6, @p7);
SELECT "Id"
FROM "Comment"
WHERE changes() = 1 AND "rowid" = last_insert_rowid() AND "PostId" = @p6;
ERR | Microsoft.EntityFrameworkCore.Update | An exception occurred in the database while saving changes for context type 'MyContext'.
Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while updating the entries. See the inner exception for details.
---> Microsoft.Data.Sqlite.SqliteException (0x80004005): SQLite Error 19: 'NOT NULL constraint failed: Comment.Id'.
at Microsoft.Data.Sqlite.SqliteException.ThrowExceptionForRC(Int32 rc, sqlite3 db)
at Microsoft.Data.Sqlite.SqliteDataReader.NextResult()
at Microsoft.Data.Sqlite.SqliteCommand.ExecuteReader(CommandBehavior behavior)
at Microsoft.Data.Sqlite.SqliteCommand.ExecuteReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken)
at Microsoft.Data.Sqlite.SqliteCommand.ExecuteDbDataReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(IList`1 entriesToSave, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(DbContext _, Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while updating the entries. See the inner exception for details.
---> Microsoft.Data.Sqlite.SqliteException (0x80004005): SQLite Error 19: 'NOT NULL constraint failed: Comment.Id'.
at Microsoft.Data.Sqlite.SqliteException.ThrowExceptionForRC(Int32 rc, sqlite3 db)
at Microsoft.Data.Sqlite.SqliteDataReader.NextResult()
at Microsoft.Data.Sqlite.SqliteCommand.ExecuteReader(CommandBehavior behavior)
at Microsoft.Data.Sqlite.SqliteCommand.ExecuteReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken)
at Microsoft.Data.Sqlite.SqliteCommand.ExecuteDbDataReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(IList`1 entriesToSave, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(DbContext _, Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
````

### Include verbose output
No applicable info.

### Include provider and version information

EF Core version: 5.0.11
Database provider: Microsoft.EntityFrameworkCore.Sqlite version 5.0.11
Target framework: .NET 5.0
Operating system: linux
IDE: vscode 1.61.0

### Extras
The [docs say](https://docs.microsoft.com/en-us/ef/core/modeling/owned-entities#implicit-keys) that the owned table has an implicit key, which explains the complaint about `Comment.Id`.

But why does this only happen for sqlite, and how do I deal with it?