UI: Make checkbox gaps slightly wider

[frostburn]

Some of the <label> elements have explicit space characters in them. This doesn't look neat in template code. The gap should be controlled by CSS alone.

[frostburn]

Assigning to Marc in reference to https://github.com/xenharmonic-devs/scale-workshop/pull/642/files#r1562023627 .

[000masa000]

copying the comment to contoinue discussion here:
for now in main.css I replaced "select-group" with "dropdown-group" and also added "checkbox-group" to match the already existing "radio-group". Not sure but it seemed to make sense that a row of each of these HTML elements might need different spacing. Any thoughts about best way to implement this?

[000masa000]

what class name should be given to labels that fall to the right of an input (checkbox, radio button, number) : these need a gap to the left of the text?

[frostburn]

what class name should be given to labels that fall to the right of an input (checkbox, radio button, number) : these need a gap to the left of the text?

I don't think they need a name. CSS rules should be able to specify label elements within a checkbox container.

[frostburn]

PR was #654