This adds the sourceMetadata column to the collections table to match
the one on documents. The column is defined as JSONB and allows null values.
Changes:
- Added migration to create sourceMetadata column on collections table
- Added sourceMetadata field to Collection model with SourceMetadata type
- Imported SourceMetadata type in Collection model
Co-authored-by: codegen-sh[bot] <131295404+codegen-sh[bot]@users.noreply.github.com>