Fix generated column in unique key error

[meiji163]

Description

This PR fixes a bug when the unique key contains a virtual column. The update query builder checks uniqueKeyColumns is a subset of sharedColumns which only contains non-virtual columns, so the migration fails.

We can reproduce the bug by adding update DML to the generated-columns-unique test case.

In case this PR introduced Go code changes:

• contributed code is using same conventions as original code
• script/cibuild returns with no formatting errors, build errors or unit test errors.

Copilot reviewed 4 out of 6 changed files in this pull request and generated 2 comments.

Files not reviewed (2)

• localtests/generated-columns-unique/create.sql: Language not supported
• localtests/generated-columns/create.sql: Language not supported

Comments suppressed due to low confidence (1)

go/sql/builder_test.go:691

• The test case should include a scenario where the unique key columns contain virtual columns to ensure the new logic is covered.

_, err := NewDMLUpdateQueryBuilder(databaseName, tableName, tableColumns, sharedColumns, sharedColumns, uniqueKeyColumns)

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[hugodorea]

Since we're creating a new instance of ColumnList, what if we turn this method into factory function? Something like:

 NewFilteredColumnList(ordinals ColumnsMap, f func(Column) bool) *ColumnList {
 ...
}

[meiji163]

really I just want to filter []Column, but IsSubsetOf is a method of ColumnList so I had to make a new one 😓