Specify table name in select for models controller

[snipe]

This fixes an issue where you might get an "ambiguous" query error depending on what you're sorting on in the Asset Models API controller.

[what-the-diff]

PR Summary

• Consistency and Clarity in Code References
  We've improved the readability of our code by consistently prefixing column references with models. This update has been implemented in the index method of AssetModelsController.php. The changes are as follows:
  • model_number is now referenced as models.model_number
  • min_amt is now referenced as models.min_amt
  • eol is now referenced as models.eol
  • created_by is now referenced as models.created_by
  • requestable is now referenced as models.requestable
  • category_id is now referenced as models.category_id
  • manufacturer_id is now referenced as models.manufacturer_id
  • depreciation_id is now referenced as models.depreciation_id
  • fieldset_id is now referenced as models.fieldset_id

This brings homogeneous code structure and makes it easier for upcoming developers to understand and navigate through our code.