Investigate removing Bootstrap as parent theme

[trubach]

In order to simplify our ILFW theme, it might be beneficial to remove 'bootstrap5' as our base/parent theme.

I'd like to use this issue as a space to document any issues that we would encounter if we attempted to do that.

If removing bootstrap5 as a parent theme would mean rewriting our entire theme, we certainly would NOT want to put the effort into doing that, but I'd like to document that in this issue.

[github-actions]

Branch nhjohnstone/issue-991-investigate-removing-bootstrap-as-parent-theme created!

[trubach]

Some issues that have been identified:

• Column width / layout: Our theme utilizes the Bootstrap column classes to control the width of our elements. The IL Toolkit has some classes available to use, but it's not clear how much effort it would take to convert our theme to use them instead.
• Form display: The OOB Bootstrap form elements are being used on our sites. Removing bootstrap would cause web forms to not be formatted as well and could cause responsive issues.

[nhjohnstone]

Creating a new subtheme from Stable9:

• create templates, move them into the new theme (will add list)
• add the theme settings from existing theme