Currently, radios with the class "btn-group" are broken in J4 as you can't change the value at all. The radio is just unresponsive to your clicking.

Summary of Changes

• Removes the special JS done in the Cassiopeia and Atum templates. Since Bootstrap is loaded anyway and it offers the same functionality, we can use just that one for now (until it gets eventually converted to a CE).
• Adjusts the JLayout for the radio formfield so it works with the Bootstrap code.
  Thanks to @C-Lodder for that work!

Testing Instructions

To test, you can add the following code to the config.xml of any extension. Eg to /administrator/components/com_content/config.xml. Just put it right after the <config> tag.

	<fieldset
		name="test"
		label="Test"
	>
		<field
			name="plain"
			type="radio"
			class=""
			default="1"
		>
			<option value="1">Foo</option>
			<option value="0">Bar</option>
		</field>

		<field
			name="btn-group"
			type="radio"
			class="btn-group"
			default="1"
		>
			<option value="1">Foo</option>
			<option value="0">Bar</option>
		</field>

		<field
			name="btn-group-yesno"
			type="radio"
			class="btn-group btn-group-yesno"
			default="1"
		>
			<option value="1">JYES</option>
			<option value="0">JNO</option>
		</field>

		<field
			name="btn-group-yesno reordered"
			type="radio"
			class="btn-group btn-group-yesno"
			default="1"
		>
			<option value="0">JNO</option>
			<option value="1">JYES</option>
		</field>

		<field
			name="switcher"
			type="radio"
			class="switcher"
			default="1"
		>
			<option value="0">JNO</option>
			<option value="1">JYES</option>
		</field>
	</fieldset>

Now go to the settings of that component. You will have a new tab with 5 parameters.
Check if the radios work.
Make also sure the plain radios and the switcher work as well.

Expected result

All radios work
We even get some styling as expected, but main point is they work ?

Actual result

The marked radios are not working (and styling doesn't exist).

Documentation Changes Required

None