[New arch] Use Moshi to parse sharees

[davigonz]

• Use Moshi to parse sharees, removing the parsing from UsersAndGroupsSearchProvider.
• Make all sharees tests non instrumented and fix already non instrumented ones, avoiding returning empty arraylist.

Tasks:

• Check how Moshi works
• Update Sharees API documentation: add example body for ocs recipient response docs#2814
• Integrate the library
• clean up parts around ShareeOperation
• Create OCSharee model object.
• get it to work

Related PRs:

• App: [New arch] Use moshi to parse sharees #2994
• Library: [New arch] Use moshi to parse sharees android-library#352