Checkbox outside of FormField should have pad="none"

[halocline]

Please describe what the rule should do:

If a Checkbox is outside of FormField, the rule should ensure that the Checkbox has the property pad="none".

Probably an HPE specific rule.

What category of rule is this? (place an "X" next to just one item)

[ ] Warns about a potential error (problem)
[x] Suggests an alternate way of doing something (suggestion)
[ ] Other (please specify:)

Provide 2-3 code examples that this rule will warn about:

Why should this rule be included in eslint-plugin-grommet?