Added assets endpoint for locations

[snipe]

This was never documented, and I'm not even sure if it ever existed, but we had a route for it. /locations/{id}/assets now returns a list of assets assigned to that location.

(This was tripping a rollbar, so I wanted to get rid of it.)

[what-the-diff]

PR Summary

• Integration of AssetsTransformer and Asset Models into LocationsController
  The LocationsController now has integration for AssetsTransformer and Asset Models which allows the controller to handle the assets data more effectively.

• New 'assets' Method in LocationsController
  A new 'assets' method has been added to the LocationsController. This method streamlines the handling of assets associated with specific locations.

• Route Update in api.php
  The 'api.php' route configuration file has been updated. This is to incorporate the new 'assets' method from the LocationsController into the application's API interfaces.

• Addition of New Test File: LocationsViewTest.php
  A new test file named 'LocationsViewTest.php' has been included in the testing suite. The file, which resides in 'tests/Feature/Locations/Api/', provides functional tests for the Locations API, ensuring accurate and reliable functionality.