format-code: option to explicitly enable linters

Sometimes it is useful to explicitly enable a single (or set of)
linters.  Add an option (`--enable <tool>`) such that if any enable
is set then only those linters will be utilized.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I49e4b760217e6a0df5c16275c466958b3a2422b3
1 file changed