Improve tests

Problem/Motivation

Currently there are some tests but these only check if the site loads ok after the module has been loaded and tests if the user can create datetime fields and that's it, we need proper tests (Javascript tests) to check the actual widgets

Steps to reproduce

Check the current tests: https://git.drupalcode.org/project/timepicker/-/blob/3.0.x/tests/src/Fun...

Missing Widget testing.

Proposed resolution

Create Javascripts tests to tests the widgets

Remaining tasks

N/A

User interface changes

N/A

API changes

N/A

Data model changes

N/A