config-clang-tidy: add format subcommand

The 'merge' subcommand can be used for formatting, if the `--reference`
is the same clang-tidy file as the input, but this is not convenient
for users.  Add a 'format' subcommand that does the expected.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: If51ded84e85f6f285a6b5d1df0764ff20b1b2064
1 file changed