Add provisional Support for blockquotes to support ckeditor 5 when using bootstrap barrio

Also added ticket here as I am not happy with how .blockquote class works in bootstrap 5.

https://github.com/twbs/bootstrap/issues/39271

I encountered this issue and worked around it by adding the mentioned css to my custom theme but not adding the css with the .blockquote class selector but adding it on the blockquote element as so,

blockquote {
  border-left: 5px solid #ccc;
  font-style: italic;
  margin-left: 0;
  margin-right: 0;
  overflow: hidden;
  padding-left: 1.5em;
  padding-right: 1.5em;
}

This is because I didn't see any classes on the rendered blockquote. My markup is,

<blockquote>
    <p>...</p>
    <p>...</p>
</blockquote>

@2dareis2do
We can extend ckEditor library with bootstrap styles files.

Ok thanks @ravi

I have just noticed there is also a ckeditor plugin that deals with this:

e.g.

https://ckeditor.com/docs/ckeditor5/latest/features/indent.html

In drupal we also have

https://www.drupal.org/project/ckeditor_indentblock →

As mentioned previously bootstrap 5 (unlike previous versions) does not seem to support either:

1. Indentation or nested indentation
2. Support for cite attribute and tag as recommended by w3c.

Also, ckeditor does not seem to support cite attribute either on native blockquote, although this can be added by adding via source editing allowed tags and attributes (although this appear to be broken in the latest version of drupal (10.2.2).

https://www.drupal.org/project/drupal/issues/3410100 🐛 [10.2 regression] CKEditor 5 breaks when "Source"/Source editing button is added and "Manually editable HTML tags" are specified Needs review

and

https://github.com/ckeditor/ckeditor5/issues/15167