`form-check-inline` support for `.*-feedback`

[zalog]

This is what it looks like:

This is the markup:

<div class="form-check form-check-inline">
  <input ... class="form-check-input is-invalid">
  <label>1</label>
  <div class="invalid-feedback">Example invalid feedback</div>
</div>
<div class="form-check form-check-inline">
  <input ... class="form-check-input">
  <label class="form-check-label">2</label>
</div>
<div class="form-check form-check-inline">
  <input ... class="form-check-input">
  <label class="form-check-label">3 (disabled)</label>
</div>

Perhaps we need to move *-feedback somewhere outside and under all .form-check-inline.

[ffoodd]

Do you have any real world use case for this?

I mean, in a fieldset containing a group of checkboxes (meaning options), I don't see how you could ever get an invalid value on a single checkbox. As a las resort, checking at least one option could be required, but it then should be carried by a containing fieldset, shouldn't it?

@patrickhlauke I'd love to have your thought about this case.

[zalog]

The real world example would be to move that message (help text, valid / invalid feedback) under all .form-check-inline.
Move it as per group, outside, as I wrote in the description :)
What do you think?

[mdo]

Wondering if this is fixed with @ysds's changes to form validation in #30170?

[zalog]

Yep, I think it's fixed in a way.
With #30170, .*-feedback are not display: none by default anymore.
Perhaps it's not documented/exemplified. I can help with this if needed.

Great work @ysds :)