[FEATURE REQUEST] Sharing NG: preliminary

[jesmrec]

As preliminary step to implement Sharing NG, the Share option in the bottom sheet should open:

• The legacy dialog for oC10, since it is still alive
• The new dialog for oCIS, with Sharing NG implementation

For that aim, the backend type should be recovered from somewhere (typically, capabilities), to choose the correct path.

In this first work, loading the fragment with the correct header and some UI changes:

Also, it should be enabled for items inside of custom spaces, depending on the permission.

Pay attention to the badges in the list of files. They work thanks to the ocs backwards compatibility, but, in oCIS this should be avoided. In PROPFIND

<oc:share-types>
          <oc:share-type>0</oc:share-type> <-- share with users/groups
          <oc:share-type>3</oc:share-type> <-- public link
</oc:share-types>

TASKS

• Research (if needed)
• Create branch feature/feature_name
• Development tasks
  • Implement whatever
  • ...
  • Implement unit tests (if needed)
• Code review and apply changes requested
• Design test plan
• QA
• Merge branch feature/feature_name into master