[Github] Add workflow to test the issue write workflow

This does not test most of the functionality (i.e., that writing to an
existing comment still works), but does ensure that the plumbing works
and things are not completely broken.

Pull Request: llvm#170209

Author: boomanaiden154

.github/workflows/issue-write-test.yaml

@@ -0,0 +1,25 @@
+name: Test Issue Write Workflow
+
+permissions:
+  contents: read
+
+on:
+  pull_request:
+    paths:
+      - '.github/workflows/issue-write-test.yaml'
+
+jobs:
+  test-issue-write:
+    name: "Test Issue Write"
+    runs-on: ubuntu-24.04
+    if: github.repository == 'llvm/llvm-project'
+    steps:
+      - name: Write Comment
+        run: |
+          echo '[{"body": "This is a comment for testing the issue write workflow"}]' > comments
+      - name: Upload Comment
+        uses: actions/upload-artifact@330a01c490aca151604b8cf639adc76d48f6c5d4 # v5.0.0
+        with:
+          name: workflow-args
+          path: |
+            comments

.github/workflows/issue-write.yml

@@ -8,6 +8,7 @@ on:
       - "PR Request Release Note"
       - "Code lint"
       - "CI Checks"
+      - "Test Issue Write"
     types:
       - completed