chore: add workflow to pull release testing issues into the BTR board

Add GH workflow that includes issues into the BTR board after the issue
is labeled with `release testing`.  Also add label needs triage for
bug triaging issues.

.github/workflows/add-issue-to-btr-project-board-yml

@@ -0,0 +1,26 @@
+name: Add release testing issues to BTR project and needs triage label
+on:
+  issues:
+    types: [labeled]
+jobs:
+  add-issue-to-project:
+    name: "Add release testing issue to project"
+    if: github.event.label.name == 'release testing'
+    uses: openedx/.github/.github/workflows/add-issue-to-a-project.yml@master
+    secrets:
+      GITHUB_APP_ID: ${{ secrets.GRAPHQL_AUTH_APP_ID }}
+      GITHUB_APP_PRIVATE_KEY: ${{ secrets.GRAPHQL_AUTH_APP_PEM }}
+    with:
+      # required, it's the numeric part of a github project url
+      # for example, https://github.com/orgs/openedx/projects/28 has PROJECT_NUMBER: 28
+      PROJECT_NUMBER: 28
+
+  add-needs-triage-label:
+    name: "Add needs triage label"
+    runs-on: ubuntu-latest
+    if: github.event.label.name == 'release testing' && !contains(github.event.issue.labels.*.name, 'needs triage')
+    steps:
+      - name: Apply needs triage label
+        uses: actions-ecosystem/action-add-labels@v1
+        with:
+          labels: needs triage