Add a style-check workflow

Add a style-check workflow

Add a CI job that evaluates style issues, restricted only to lines
changed for the affected files in a given commit

Also provide a mechanism to waive those style issues.  by applying the
style:exempted label to a PR, the checks are still run (its nice to see
what they are regardless), but the test will pass CI regardless of
weather any issues are found.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
(Merged from https://github.com/openssl/openssl/pull/24806)