bootstrap_field addon_before_class and addon_after_class feature incomplete

[isolationism]

Per the bootstrap_field feature documentation, a None value may be supplied to the templatetag to render an input group without wrapping <span> tags:

django-bootstrap5/src/django_bootstrap5/templatetags/django_bootstrap5.py

Line 444 in dacc14f

Set to None to disable the span inside the addon. (for use with buttons)

... But the feature is not implemented. According to the following lines:

django-bootstrap5/src/django_bootstrap5/renderers.py

Lines 491 to 496 in dacc14f

	addon_before = (
	format_html('<span class="input-group-text">{}</span>', self.addon_before) if self.addon_before else ""
	)
	addon_after = (
	format_html('<span class="input-group-text">{}</span>', self.addon_after) if self.addon_after else ""
	)

... If either addon_before or addon_after are defined, the wrapper tags and their classes are hard-coded instead of using the values self.addon_before_class and/or self.addon_after_class as defined here:

django-bootstrap5/src/django_bootstrap5/renderers.py

Lines 212 to 217 in dacc14f

	self.addon_before_class = kwargs.get(
	"addon_before_class", self.widget.attrs.pop("addon_before_class", "input-group-text")
	)
	self.addon_after_class = kwargs.get(
	"addon_after_class", self.widget.attrs.pop("addon_after_class", "input-group-text")
	)

Since these values are ignored, neither can the classes be changed to another value, nor can they be nullified for the case of rendering a button.

[isolationism]

Duplicate of #153