remove <BsForm::Group> component

[jelhan]

This removes the <BsForm::Group> component, which was yielded as group from <BsForm>. It provided some value for Bootstrap 3. But due to some changes in Bootstrap 4 (and 5) markup related to form validation, it wasn't provided much value anymore for recent Bootstrap version.

Please see #1629 for more context.

Migration

Bootstrap 4

Before

<BsForm as |form|>
  <form.group>
    {{! some content }}
  </form.group>
</BsForm>

After

<BsForm>
  <div class="form-group">
    {{! some content }}
  </div> 
</BsForm>

If @formLayout is "horizontal", you need to add "row" class to <div class="form-group"> additionally.

Bootstrap 5

Before

<BsForm as |form|>
  <form.group>
    {{! some content }}
  </form.group>
</BsForm>

After

<BsForm>
  <div>
    {{! some content }}
  </div> 
</BsForm>

If @formLayout is "horizontal", you need to add "row" class to <div class="form-group"> additionally.

[simonihmig]

Thank you!