ActivityPub integration test (#4761)

* feat(test): add an end-to-end ActivityPub integration test

* chore(ci): run AP integration test under CI

* feat(test): use caddy instead of home built reverse proxy

* fix(test): fix linter warnings

* chore(test): don't commit test self-signed certs I suppose

* chore(test): more shellcheck linter warnings

* fix: fix test setup under CI

test/automated/activitypub/run.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+
+# Run the ActivityPub federation test
+#
+# Usage:
+#   ./run.sh                    # Run with 100 users
+#   USER_COUNT=50 ./run.sh      # Run with 50 users
+#   KEEP_RUNNING=true ./run.sh  # Keep servers running after test
+#
+# Prerequisites:
+#   Add to /etc/hosts: 127.0.0.1 owncast.local snac.local
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+exec "${SCRIPT_DIR}/test-federation.sh" "$@"