External components: optional configurable path for git source (#6677)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>

esphome/config_validation.py

@@ -2124,6 +2124,7 @@ GIT_SCHEMA = Schema(
         Optional(CONF_REF): git_ref,
         Optional(CONF_USERNAME): string,
         Optional(CONF_PASSWORD): string,
+        Optional(CONF_PATH): string,
     }
 )
 LOCAL_SCHEMA = Schema(