Use advice_if_enabled() API to rewrite a simple pattern to
call advise() after checking advice_enabled().
* rj/use-adv-if-enabled:
add: use advise_if_enabled for ADVICE_ADD_EMBEDDED_REPO
add: use advise_if_enabled for ADVICE_ADD_EMPTY_PATHSPEC
add: use advise_if_enabled for ADVICE_ADD_IGNORED_FILE