Avoid unnecessarily hydrating models on asset model show page

[marcusmoore]

Description

This PR avoids hydrating models that are only used for displaying the related count on the asset model show page.

Before:

After:

(hydrated model count is being displayed in debugbar)

Type of change

• Bug fix (non-breaking change which fixes an issue)

[shortcut-integration]

This pull request has been linked to Shortcut Story #20686: Symfony\Component\ErrorHandler\Error\FatalError: Allowed memory size of 205520896 bytes exhausted (tried to allocate 14527888 bytes).

[what-the-diff]

PR Summary

• Added New Method to AssetModelsController
  The 'AssetModelsController' has received an update to improve efficiency. We've added a new method, referred to as 'withCount('assets')'. This is now part of the 'show' function within the class. This method is designed to rapidly count the total number of assets linked with a specific model.

• Updated Display Condition in View Blade
  We've also made alterations to the conditions used to display the count of assets in 'view.blade.php'. Before, it used to show the asset count only when $model->assets->count() > 0; that is, only when there were more than zero assets associated with the model. Now, it has been optimised to display the asset count when $model->assets_count > 0. This change brings a quicker response time and an improved user interface experience.