* Refactor user's device assignment logic
* Extract device assignment logic into app methods
* Move device retrieval into control flow
* Move un\assign logic into control flow
* Extract mobile callflow update into own function
* Patch device owner_id instead of full update
* Move mobile callflow id retrieval to control flow
* Patch callflow to avoid having to retrieve it first
* Consolidate un\assignment logic
* Migrate single-used app methods into closure
* Extract mobile callflow update logic into app method
* Run device patch and mobile callflow update in parallel
* Move back device assignment logic to users module
* Consolidate mobile callflow update w/ user callfow fetching logic
* Update linked callflow on mobile device un\assignment
* Refactor entities update logic on device un\assignment