Replace Glyphicons with Bootstrap Icons

[liamkeily]

To help with the Bootstrap 5 upgrade #973 I have taken the icon related changes from the other branch and fixed some of the issues. This seems like something we could potentially merge first to help remove distractions from the other PR.

Merge request checklist

• I read the guidelines for contributing
• I created my branch from dev and I am issuing the PR to dev
• I didn't pushed the dist directory
• If it's a new feature, I added the necessary unit tests
• If it's a new language, I filled the __locale and __author fields

Before

After

[mistic100]

I don't see the point, the BT5 support won't be merged/released until you declare the merge request ready. No point in releasing only the icons.

[liamkeily]

Glyphicons is no longer supported by Bootstrap 5 but Bootstrap Icons appears to work regardless of Bootstrap version.

Use them with or without Bootstrap in any project.

I thought breaking this part out would help to reduce the diff of the Bootstrap 5 related stuff to help with reviewing / testing / fixing the remaining issues.

[liamkeily]

Carried this on here #992