Administration: make main components overridable

[Pineirin]

Remove unused components
Add missing translations
closes: #102

[Pineirin]

I didn't manage to fix the tests. Currently, for jest to work, we need to specify the dependencies needed for the tests in the file https://github.com/inveniosoftware/invenio-administration/blob/main/invenio_administration/assets/semantic-ui/js/invenio_administration/package.json.

The issue lays in the translations, as we cannot define in the package.json the alias we use for importing the translations, as can be seen in the error.
In theory the solution is to mock the import using Mock Functions (https://jestjs.io/docs/mock-function-api#mockfnmockreturnvaluevalue), but I don't properly understand how mock functions can be used to mock an import of an import.

[kpsherva]

closing due to changed naming policy of overridable ids