Generate sql_exporter config files with Jsonnet

There are quite a few benefits to this approach:

- Reduce config duplication
  - The two sql_exporter configs were super similar with just a few
    differences
- Pull SQL queries into standalone files
  - That means we could run a SQL formatter on the file in the future
  - It also means access to syntax highlighting
- In the future, run different queries for different PG versions
  - This is relevant because right now, we have queries that are failing
    on PG 17 due to catalog updates

Signed-off-by: Tristan Partin <tristan@neon.tech>

.github/workflows/build_and_test.yml

@@ -120,6 +120,25 @@ jobs:
       - name: Run mypy to check types
         run: poetry run mypy .
 
+  check-codestyle-jsonnet:
+    needs: [ check-permissions, build-build-tools-image ]
+    runs-on: [ self-hosted, small ]
+    container:
+      image: ${{ needs.build-build-tools-image.outputs.image }}
+      credentials:
+        username: ${{ secrets.NEON_DOCKERHUB_USERNAME }}
+        password: ${{ secrets.NEON_DOCKERHUB_PASSWORD }}
+      options: --init
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Check Jsonnet code formatting
+        run: |
+          jsonnetfmt --test \
+            $(find . -type f -name '*.jsonnet' -o -name '*.libsonnet')
+
   # Check that the vendor/postgres-* submodules point to the
   # corresponding REL_*_STABLE_neon branches.
   check-submodules: