refactor(dev-infra): refactor commit-message files (#38845)

Refactor the commit-message files to be consistent with how other ng-dev tooling
is structured.

PR Close #38845

dev-infra/commit-message/config.ts

@@ -8,6 +8,7 @@
 
 import {assertNoErrors, getConfig, NgDevConfig} from '../utils/config';
 
+/** Configuration for commit-message comands. */
 export interface CommitMessageConfig {
   maxLineLength: number;
   minBodyLength: number;