Please be clearer about the meaning of the <MigrationTimestamp>_<MigrationName>.Designer.cs file

While this page describes the different files involved in an EF Core migration, it could be clearer about each of their roles. For example, what is the difference between the <ContextName>Snapshot.cs file and each <MigrationTimestamp>_<MigrationName>.Designer.cs file? What does EF Core use each of these files for? Convention suggests that we should keep our hands off the Designer.cs file, whereas it isn't as clear as to whether we can safely edit the Snapshot.cs file (although I don't).

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* ID: 6e28b0a8-b7e4-4c07-9e60-0df403bbee28
* Version Independent ID: 12300b31-6f7b-b75c-970d-693365e77013
* Content: [Migrations - EF Core](https://docs.microsoft.com/en-us/ef/core/managing-schemas/migrations/)
* Content Source: [entity-framework/core/managing-schemas/migrations/index.md](https://github.com/aspnet/EntityFramework.Docs/blob/master/entity-framework/core/managing-schemas/migrations/index.md)
* Product: **entity-framework**
* Technology: **entity-framework-core**
* GitHub Login: @bricelam
* Microsoft Alias: **bricelam**