Closes #14740: Remove BootstrapMixin (#14841)

* Introduce custom form widget templates to apply CSS classes

* Apply both mandatory and optional CSS classes to form widgets

* Omit required & placeholder attrs

* Move annotation of field validation failures to CSS

* Remove BootstrapMixin class

* Remove obsolete ComponentTemplateImportForm class

* Remove obsolete custom forms for login & password change

* Clean up obsolete accommodations for 'required' widget attr

netbox/extras/forms/scripts.py

@@ -2,7 +2,6 @@ from django import forms
 from django.utils.translation import gettext_lazy as _
 
 from extras.choices import DurationChoices
-from utilities.forms import BootstrapMixin
 from utilities.forms.widgets import DateTimePicker, NumberWithOptions
 from utilities.utils import local_now
 
@@ -11,7 +10,7 @@ __all__ = (
 )
 
 
-class ScriptForm(BootstrapMixin, forms.Form):
+class ScriptForm(forms.Form):
     _commit = forms.BooleanField(
         required=False,
         initial=True,