Merge branch 'create_vertex_gitlab_docs_model' into 'master'

Add model and DB tables to support vertex embeddings for docs

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/129917



Merged-by: Prabakaran Murugesan <pmurugesan@gitlab.com>
Approved-by: Prabakaran Murugesan <pmurugesan@gitlab.com>
Reviewed-by: Alexandru Croitor <acroitor@gitlab.com>
Reviewed-by: Nicolas Dular <ndular@gitlab.com>
Reviewed-by: Sincheol (David) Kim <dkim@gitlab.com>
Reviewed-by: Prabakaran Murugesan <pmurugesan@gitlab.com>
Co-authored-by: Alexandru Croitor <acroitor@gitlab.com>