Return metadata sorted and with hierarchy

In the frontend, we want to show a hierarchy similar to https://openeduhub.github.io/lrmi-profile/draft/

Further ToDo's:

[ ] Where do I need to actually get source back? Does quality need this -> performance optimization
[ ] Fixing broken collections without content
[x] Fixing broken collections display
[x] Refactor get_properties to only get properties for https://openeduhub.github.io/lrmi-profile/draft/
- [ ] check if I can autogenerate this from API or somewhere
[x] Refactor data model to return one line with "total" which is presented as total number of sources
[x] Refactor data model to return level for each line
[x] Sort lines by metadatum
[x] https://github.com/openeduhub/metaqs-main/issues/38

Refactoring:

[ ] Refactor global storage, see https://github.com/openeduhub/metaqs-main/pull/69#discussion_r927460936
[ ] Refactor elastic search attribute objects
[x] RefactorCOLLECTION_NAME_TO_ID
[x] Centralize REPLICATION_SOURCE https://github.com/openeduhub/metaqs-main/pull/69#discussion_r927429395
[x] Refactor Collections

Consider:

openeduhub / metaqs-main