refactor: rewriting some e2e tests

[EduardoJM]

The fundamental of this PR is:

1. We have some things: ArrayField widget and Inlines that works exactly same and we have a lot of duplicated test code.
2. We have the widget with various common things with ArrayField widget and Inline that have a lot of duplicated test code too.

The concept of this refactor is:

1. Create some test helper and mixins classes to run some common test-case's for each of this.
2. Make various tests inside a one test function to reduce the quantity of new browser/page opened.
3. Remove UI Regression tests for now.
4. Fix any found behaviour mistake.
5. Turn the test code more semantic and readable.

Relation to the Issues:
closes #208
closes #207

Other informations:

---

Removed major and minor version comparsion in some tests, like bellow code. The Django 4.2 is, now, the minimum supported version:

major, minor, _, _, _ = django.VERSION
if major < 4 or minor < 2:
    # Theme toggle is added in django 4.2
    # https://docs.djangoproject.com/en/4.2/releases/4.2/#django-contrib-admin
    return

---

As we removed some font tags, because we dropped support for old django (with different font names), various snapshots for UI Regression Tests are regenerated due diference into fonts.