FIX TextCheckboxGroupField should passthrough if it has only one child

[ScopeyNZ]

Currently if a developer removes the checkbox it will render a small gap on the side of the text field. This will prevent that.

cc @scott1702

[ScopeyNZ]

First try!

[scott1702]

Can confirm this works for me! Should be worth noting that this fix is only required because the only way we've been able to remove the isDisplayed checkbox is with:

$fields->removeByName('ShowTitle');
$fields->fieldByName('Root.Main.Title')->setTitle('Title');

[ScopeyNZ]

Tests should be fixed by #516

[robbieaverill]

So it becomes a text checkbox group without a checkbox? Wouldn’t it be better to remove the group and use a simple text field for the title?

[ScopeyNZ]

Yeah I was noting the redundancy of this fix as I did it. Currently it's not so easy for reasons I haven't quite nailed down yet. I figure this at least handles this situation in case somebody does similar...

[robbieaverill]

Probably because CompositeFields don't have names, so they're hard to target via $fields->removeByName() 😆

[robbieaverill]

Could use a comment, but not a blocker I did this while rebasing to get the tests green.