Exclusion of Inactive, Disabled, Support, and Service Users from Sharing Dialogs

**As** a normal user of ownCloud Infinite Scale,
**I want** to only see active and regular users in the sharing dialogs,
**So that** I can easily find and share with the relevant people without being overwhelmed by inactive, disabled, support, and service accounts.

**Acceptance Criteria:**

1. When I access the sharing dialog, I should only see a list of active and regular users.
2. Any user account that is labeled as 'inactive', 'disabled', 'support', or 'service' or is stored in another realm should not appear in the sharing dialog list.
3. The search functionality within the sharing dialog should also filter out the aforementioned types of accounts, returning only active and regular users in the search results.

/cc @tbsbdr @wkloucek @micbar @JammingBen