feat: Add code coverage to CI

.github/workflows/generate_coverage.yml

@@ -0,0 +1,68 @@
+name: generate_coverage
+
+on:
+  workflow_call
+
+jobs:
+  grcov:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Taskwarrior
+        uses: ./.github/actions/install-taskwarrior
+        with:
+          secret_gh_token: ${{ secrets.GITHUB_TOKEN }}
+      - run: |
+          # prepare taskwarrior, initial setup
+          task rc.confirmation=off || echo 0
+
+      - name: Install Rust toolchain for grcov compilation
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+      - name: Install grcov
+        uses: clechasseur/rs-cargo@v2
+        with:
+          command: install
+          args: grcov
+
+      - name: Install Rust toolchain
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          toolchain: nightly
+          override: true
+          components: llvm-tools-preview
+      - name: Checkout testdata
+        uses: actions/checkout@v4
+        with:
+          repository: kdheepak/taskwarrior-testdata
+          path: taskwarrior-testdata    
+      - name: Build taskwarrior-tui with coverage
+        uses: clechasseur/rs-cargo@v2
+        with:
+          command: build
+        env:
+          RUSTFLAGS: "-Cinstrument-coverage"  
+      - name: Run taskwarrior-tui tests in coverage environment
+        uses: clechasseur/rs-cargo@v2
+        with:
+          command: test
+          args: --workspace -- --nocapture
+        env:
+          TASKRC: taskwarrior-testdata/.taskrc
+          TASKDATA: taskwarrior-testdata/.task
+          RUST_BACKTRACE: full
+          RUSTFLAGS: "-Cinstrument-coverage"
+          LLVM_PROFILE_FILE: "your_name-%p-%m.profraw"
+
+      - name: Gather coverage data
+        run: |
+          mkdir ./target/debug/coverage/
+          grcov . -s . --binary-path ./target/debug/ -t lcov --branch --ignore-not-existing -o ./target/debug/coverage/
+        shell: bash
+      - name: Coveralls upload
+        uses: coverallsapp/github-action@v2
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          file: ./target/debug/coverage/lcov