Testing Keycloak with nightly Quarkus releases (#23407)

Closes #23322

Signed-off-by: Peter Zaoral <pzaoral@redhat.com>

.github/scripts/prepare-quarkus-next.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+set -xeuo pipefail
+
+git checkout -b new-quarkus-next origin/main
+
+if ! grep -q '<repositories>' pom.xml; then
+  sed -i '/<\/project>/i \
+          <repositories> \
+          </repositories>' pom.xml
+fi
+
+# Insert the <repository> element before the closing </repositories> tag
+sed -i '/<\/repositories>/i \
+        <repository> \
+        <id>sonatype-snapshots</id> \
+        <name>Sonatype Snapshots</name> \
+        <url>https://s01.oss.sonatype.org/content/repositories/snapshots/</url> \
+        <snapshots> \
+            <enabled>true</enabled> \
+            <updatePolicy>daily</updatePolicy> \
+        </snapshots> \
+        <releases> \
+            <enabled>false</enabled> \
+        </releases> \
+        </repository>' pom.xml
+
+./mvnw -B versions:set-property -Dproperty=quarkus.version -DnewVersion=999-SNAPSHOT
+./mvnw -B versions:set-property -Dproperty=quarkus.build.version -DnewVersion=999-SNAPSHOT
+git commit -am "Set quarkus version to 999-SNAPSHOT"
+
+snapshot_version_hash=$(git log origin/quarkus-next --grep="Set quarkus version to 999-SNAPSHOT" --format="%H" -n 1)
+commits_to_cherry_pick=$(git rev-list --right-only --no-merges --reverse new-quarkus-next...origin/quarkus-next | grep -vE "$snapshot_version_hash" || echo "")
+
+if [ -z "$commits_to_cherry_pick" ]; then
+  echo "Nothing to cherry-pick."
+else
+  for commit in $commits_to_cherry_pick
+  do
+    if git cherry-pick "$commit"; then
+      echo "Successfully cherry-picked $commit"
+    else
+      echo "Failed to cherry-pick $commit"
+      exit 1
+    fi
+  done
+fi