widget-services: remove applyViewChanges in favour of axHeartbeat

[x1B]

The applyViewChanges method can be replaced by axHeartbeat to avoid complicating our APIs.

[alex3683]

Implemented on master (v2.0.0).

Breaking Change

Support for the applyViewChanges function of widget adapters was removed and will no longer be called on heartbeat tick. Instead, widget adapters that need to act on heartbeat tick (e.g. the AngularJS adapter) now have to register themselves.

Example:

export function bootstrap( modules, laxarServices ) {
   // ...
   laxarServices.heartbeat.registerHeartbeatListener( () => { $rootScope.$digest(); } );
   // ...
   return {
      create,
      serviceDecorators,
      technology
   };
}

Before it was:

export function bootstrap( modules, laxarServices ) {
   // ...
   return {
      create,
      serviceDecorators,
      technology,
      applyViewChanges() { $rootScope.$digest(); }
   };
}