ci: add auto-add-to-project caller workflow (#34)

## Summary

Add `auto-add-to-project.yml` caller workflow: automatically adds new
issues and PRs to [Octo Board (Project
#2)](https://github.com/orgs/Mininglamp-OSS/projects/2) when they are
opened.

Calls the org-level reusable workflow at
`Mininglamp-OSS/.github/.github/workflows/auto-add-to-project.yml@main`.

## Dependency

Requires
[Mininglamp-OSS/.github#12](Mininglamp-OSS/.github#12)
to be merged first.

---------

Co-authored-by: Octo Bot <octo-bot@mininglamp.com>

Author: lml2468

.github/workflows/auto-add-to-project.yml

@@ -0,0 +1,16 @@
+# Automatically add new issues and PRs to the org-level GitHub Project.
+name: Auto add to project
+
+on:
+  issues:
+    types: [opened]
+  pull_request_target:
+    types: [opened]
+
+permissions: {}
+
+jobs:
+  add-to-project:
+    uses: Mininglamp-OSS/.github/.github/workflows/auto-add-to-project.yml@239d0b47cfe1947d5e6de826e795feac4ed90562
+    secrets:
+      PROJECT_TOKEN: ${{ secrets.PROJECT_TOKEN }}