chore: Move core tests into apps/core (OSS Migration) [LET-4169] (#4376)

* add a bunch of test to oss

* symlink and auto-detect dir

* symlink the other direction

* add pull_request_target logic

* remove undertaker and add alembic validation

* symlink doesn't work with gh actions and add validation workflow to ensure actions in cloud and oss are lockstep

* sync these

* specify extras selectively

.github/workflows/core-lint.yml

@@ -0,0 +1,63 @@
+name: 🐍🧹 [Core] Lint and Test
+
+on:
+  pull_request:
+    branches: [ main ]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
+
+jobs:
+  changed-files:
+    runs-on: ubuntu-latest
+    name: changed-files
+    outputs:
+      all_changed_files: ${{ steps.changed-files.outputs.all_changed_files }}
+      any_changed: ${{ steps.changed-files.outputs.any_changed }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Get changed files
+        id: changed-files
+        uses: tj-actions/changed-files@v44
+        with:
+          files: |
+            apps/core/**
+            .github/workflows/core-lint.yml
+  main:
+    needs: [ changed-files ]
+    if: ${{ needs.changed-files.outputs.any_changed == 'true' }}
+    runs-on: [self-hosted, medium]
+    strategy:
+      matrix:
+        python-version: ["3.12"]  # Adjust Python version matrix if needed
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Install dependencies
+      shell: bash
+      working-directory: apps/core
+      run: uv sync --no-install-project ${{ inputs.install-args || '--extra postgres --extra external-tools --extra dev --extra cloud-tool-sandbox' }}
+    - name: Validate PR Title
+      if: github.event_name == 'pull_request'
+      uses: amannn/action-semantic-pull-request@v5
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Run Pyright
+      uses: jakebailey/pyright-action@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+        level: "error"
+      continue-on-error: true
+
+    - name: Run Ruff Check
+      working-directory: apps/core
+      run: uv run ruff check --config pyproject.toml --diff .
+
+    - name: Run Ruff Format
+      working-directory: apps/core
+      run: uv run ruff format --config pyproject.toml --check --diff .