Add GitHub workflow for checking code format (manatee-project#46)

This PR solves manatee-project#17 

Add an Action to enforce Go code formatting using `gofmt` and block
unformatted code. This PR intentionally excludes lint since it requires
external dependencies. It also intentionally doesn't auto-commit
formatted code on push, as preferences vary.

#### Changes
- **Workflow**: `lint.yaml` checks formatting using `gofmt`. Named
"lint.yaml" instead of "check-format.yaml" because it's meant to be
extended in the future.

#### Future Improvements
1. Consider other lint options such as line length, typo, and
case-consistency.
2. Consider auto-committing format/lint fixes after making a PR.

#### Usage
- **Locally**:
  - Run `bazelisk run @go_sdk//:bin/gofmt -- -w .`
- **CI/CD**:
  - Runs on `pull_request`.

Author: hiuns

.github/workflows/lint.yaml

@@ -0,0 +1,28 @@
+on:
+  pull_request:
+    branches: [main]
+jobs:
+  format:
+    name: Enforce Code Format
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v4
+      - name: Set up Bazel
+        uses: bazel-contrib/setup-bazel@0.9.0
+        with:
+          bazelisk-cache: true
+          disk-cache: ${{ github.workflow }}
+          repository-cache: true
+      - name: Check code format
+        run: |
+          bazelisk run @go_sdk//:bin/gofmt -- -l . > gofmt_output.txt || true
+          if [ -s gofmt_output.txt ]; then
+            echo "Following files are not properly formatted:"
+            cat gofmt_output.txt
+            echo "Please run: bazelisk run @go_sdk//:bin/gofmt -- -w ."
+            exit 1
+          else
+            echo "All files are properly formatted!"
+          fi
+