Add create_foreign_key migration utility

[jdavcs]

Required for #16003 (see discussion in backend channel)

This should be used when altering a table that includes adding a column with a foreign key constraint [ref].

So, this is incorrect:

def upgrade():
    add_column(my-table, my-column-with-foreign-key-passed-as-argument)

This is correct:

def upgrade():
    with transaction():
        add_column(my-table, my-column)
        create_foreign_key(fkey-name, table-name, ref-table-name, [columns], [ref-columns])

How to test the changes?

(Select all options that apply)

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. Add a revision that adds a column to an existing table that is a foreign key.
  2. Try using the incorrect version. Run upgrade, then downgrade. Observe error on SQLite (postgres is fine)
  3. You may have to run downgrade in repair mode to fix your database.
  4. Try using the correct version. Observe no error.

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[davelopez]

Many thanks for taking the time to look into this and for the quick fix! 🍻