[TESTS] Enhance PowerGrid Fields tests

[dansysanalyst]

⚡ PowerGrid - Pull Request

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Motivation

• Bug fix
• Enhancement
• New feature
• Breaking change

Description

This Pull Request aims to enhance the tests for PowerGrid Fields, covering the following topics:

• Automatic usage of htmlentities via Laravel's e() helper in PowerGrid::fields->add();
• No utilization of the e() helper in PowerGrid Custom Fields PowerGrid::fields->add('field', closure);
• Automatic removal of <script> tag in Custom Fields;
• Table with Model Casting (string, decimal, float and boolean) and nullable fields.

Documentation

This PR requires Documentation update?

• Yes
• No
• I have already submitted a Documentation pull request.