Create autoresponder for pausing community contributions (#61)

* Create autoresponder for pausing community contributions

We're going to take a step back and redesign the volunteering model for Exercism.
Please see [this forum post](https://forum.exercism.org/t/freeing-our-maintainers-exercism-wide-changes-to-track-repositories/1109) for context.

This PR adds an autoresponder that runs when an issue or PR is opened. If the person opening the issue is not a member of the Exercism organization, the autoresponder posts a comment and closes the issue. In the comment the author is directed to discuss the issue in the forum.

If the discussion in the forum results in the issue/PR being approved, a maintainer or staff member will reopen it.

Please feel free to merge this PR. It will be merged on December 1st, 2022. Please do not close it.

If you wish to discuss this, please do so in [the forum post](https://forum.exercism.org/t/freeing-our-maintainers-exercism-wide-changes-to-track-repositories/1109) rather than here.

* Update workflow for pausing community contributions

This removes duplicated logic, relying on a shared workflow.

Author: kytrinyx

.github/workflows/pause-community-contributions.yml

@@ -0,0 +1,21 @@
+name: Pause Community Contributions
+
+on:
+  issues:
+    types:
+      - opened
+  pull_request_target:
+    types:
+      - opened
+  workflow_dispatch:
+
+permissions:
+  issues: write
+  pull-requests: write
+
+jobs:
+  pause:
+    if: github.repository_owner == 'exercism' # Stops this job from running on forks
+    uses: exercism/github-actions/.github/workflows/community-contributions.yml@main
+    with:
+      forum_category: support