feat(git_metrics): add option to ignore submodules (#5052)

* add docs

* update schema

* ok, actually update schema

* add test

* fix lint

* accidentally included my .devenv directory

.github/config-schema.json

@@ -576,6 +576,7 @@
         "deleted_style": "bold red",
         "disabled": true,
         "format": "([+$added]($added_style) )([-$deleted]($deleted_style) )",
+        "ignore_submodules": false,
         "only_nonzero_diffs": true
       },
       "allOf": [
@@ -3188,6 +3189,10 @@
         "disabled": {
           "default": true,
           "type": "boolean"
+        },
+        "ignore_submodules": {
+          "default": false,
+          "type": "boolean"
         }
       },
       "additionalProperties": false