sql: support forward indexing on tsvector

**Describe the problem**

Given a table created using the following SQL

```
CREATE TABLE "Blogs" (
"Description" text,
"Title" text NOT NULL
);
```

Run the following SQL to create a new index

```
CREATE INDEX ""IX_Blogs_Title_Description"" ON ""Blogs"" (to_tsvector('simple', ""Title"" || ' ' || coalesce(""Description"", '')));
```

The following error is returned

```
42P16: index element to_tsvector('simple', ("Title" || ' ') || COALESCE("Description", '')) of type tsvector is not indexable in a non-inverted index
```

**Additional context**
This affects efcore.pg tests

@fqazi

Jira issue: CRDB-31636