Cleanup and prepare v0.15.0

[mikkonie]

Minor Tasks

• [x] Fix incorrect references to ZoneUpdateRequiredPermissionMixin in comments
• [x] Rename _update_cache_rows() (1)
• [x] Fix sodar-oa-alert-* template IDs and classes
• [x] Remove unnecessary slug/kwarg args from OBOFormatOntologyListView
• [x] Document template_output_dir_display setting
• [x] Remove taskflow link from SODAR Core settings in admin_settings.rst
• [x] Update FontAwesome icon comments
• [x] Unify title case in get_statistics() implementations
• [x] Add missing site-wide apps in admin_ui.rst
• [x] Update wheel dependency in CI
• [x] Update assay app plugin descriptions in docs

Issues to Add in CHANGELOG

• [x] #1931
• [x] #1952

Release Checklist

• [x] Review code style and cleanup
• [x] Review and update docs entries
• [x] Update SODAR_API_DEFAULT_VERSION and SODAR_API_ALLOWED_VERSIONS
• [x] Run npx update-browserslist-db@latest for Vue app
• [x] Update Vue app version with npm version
• [x] Update version in CHANGELOG and SODAR Release Notes doc
• [x] Update version in docs conf.py
• [x] Ensure both SODAR and SODAR Core API versioning is correct in API docs
• [x] Ensure docs can be built without errors

Notes

1. Do this after merging #1946.

[mikkonie]

Done.