MerginApi class refactoring

[tomasMizera]

• Drop any support for ::OLD server type (prior to workspaces), including API calls and classes (Make sure to log error and show big red error banner that this server version is not supported anymore)
• Clean up ping:
  • Remove version check & api version status (should be read from /config)
  • Remove supports_subscription check (should be read from /config ~> if server type is ::SAAS)
• Drop merginsubscriptioninfo class (use /v2/workspaces/<id>/service instead)
• Drop / refactor merginsubscriptionstatus class
• Drop serverwasupgraded
• Rename prefix Mergin to MM... 😇
• Get rid of the auth event loop (Likely, see

  mobile/core/merginapi.cpp

  Line 3120 in 703d5a4

  // This is an ugly fix for #3261: if the user was logged in, but the token was already expired

  and When app starts there is a notification that auth token is missing - but then the account loads OK in another moment #3261)
• Drop userID - we do not need it (done in Cache user profile data and fix usage of userauth and userinfo #3964)
• Drop apiVersionStatus - it clashes with other calls ... some calls like "refreshUserRole" randomly won't execute if this one is not loaded yet
• Add button not visible for editor/writer access rights in mobile app – cannot add new record #4015
• Define startup behaviors (new server, new installation, project preopened, server changes, offline, expired token, password, sso)
• Decouple supportsSelectiveSync (Decouple selective sync #4719)

[tomasMizera]

Make sure to handle #4015 too