Invenio-banners

- Moved admin menu item for banners to site administration category

- installation: bump invenio-administration

- ui: remove bottom margin

- remove deprecated flask-babelex imports
- install invenio-i18n explicitly

- global: refactor into resource/service pattern
- global: implement CRUD operations
- global: implement best practices for packaging (declarative cfg), code
linting (black) and testing
- search: improve banners search by query params
- administration: integrate banners view module

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- Initial public release.