Add dependency submission (#1523)

This adds jobs to add Gradle dependencies to [GitHub's dependency
submission
API](https://docs.github.com/en/code-security/how-tos/secure-your-supply-chain/secure-your-dependencies/using-the-dependency-submission-api),
and to review when these dependencies change.

.github/dependabot.yml

@@ -1,6 +1,8 @@
 version: 2
 updates:
 - package-ecosystem: github-actions
+  cooldown:
+    default-days: 7
   directory: /
   ignore:
   - dependency-name: '*'