Add save-qlt-cache, bundle-codeql-packs, run-qlt-unit-tests actions

Companion actions to the extended install-qlt: save-qlt-cache persists its
cache-dir/cache-primary-key outputs, bundle-codeql-packs wraps `codeql pack bundle`
for a data-driven list of packs, and run-qlt-unit-tests wraps `qlt test run
execute-unit-tests`/`validate-unit-tests` for a single language.

Author: mbaluda

.github/actions/bundle-codeql-packs/action.yml

@@ -0,0 +1,38 @@
+name: Bundle CodeQL packs
+description: |
+  Bundles a set of CodeQL query packs via `codeql pack bundle`, reusing the cache
+  directory populated by the `install-qlt` action. This wraps the CLI directly rather than
+  a `qlt pack` subcommand, since QLT's own pack-publication CLI surface wasn't verified
+  when this action was written; it can be swapped for a native `qlt pack bundle` call
+  once that's confirmed.
+inputs:
+  codeql-bin:
+    description: Path to the `codeql` binary, e.g. the `codeql-bin` output of `install-qlt`.
+    required: true
+
+  cache-dir:
+    description: The cache directory to pass as `--common-caches`, e.g. the `cache-dir` output of `install-qlt`.
+    required: true
+
+  packs:
+    description: |
+      One `<output-file>.tgz <pack-src-path>` pair per line, e.g.:
+        common-cpp-coding-standards.tgz cpp/common/src
+        common-c-coding-standards.tgz c/common/src
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - name: Bundle packs
+      shell: bash
+      env:
+        CODEQL_BIN: ${{ inputs.codeql-bin }}
+        CACHE_DIR: ${{ inputs.cache-dir }}
+        PACKS: ${{ inputs.packs }}
+      run: |
+        while read -r output pack_path; do
+          [ -z "$output" ] && continue
+          echo "::debug::Bundling $pack_path -> $output"
+          "$CODEQL_BIN" pack bundle --common-caches="$CACHE_DIR" --output="$output" "$pack_path"
+        done <<< "$PACKS"

.github/actions/run-qlt-unit-tests/action.yml

@@ -0,0 +1,64 @@
+name: Run and validate CodeQL unit tests via QLT
+description: |
+  Runs the repository's unit tests for a given language via `qlt test run
+  execute-unit-tests`, then validates the results via `qlt test run
+  validate-unit-tests`, failing the step if any test failed.
+
+  Replaces a hand-rolled `codeql test run` slicing script plus a separate
+  results-validation job with QLT's own test-running/validation subcommands.
+  Unverified: whether QLT's runner supports the same degree of parallelism/RAM
+  tuning as the `--slice`/`--ram` flags used by the script it replaces.
+inputs:
+  language:
+    description: The language to run tests for, e.g. `cpp` or `c`.
+    required: true
+
+  num-threads:
+    description: Number of threads to use for the test runner.
+    required: false
+    default: "8"
+
+  work-dir:
+    description: Where to place intermediate execution output files.
+    required: false
+    default: ${{ runner.temp }}
+
+  base:
+    description: The base path to find the query repository.
+    required: false
+    default: ${{ github.workspace }}
+
+  codeql-args:
+    description: Extra arguments to pass through to CodeQL.
+    required: false
+    default: ""
+
+outputs:
+  results-directory:
+    description: The directory containing the raw test execution results.
+    value: ${{ inputs.work-dir }}
+
+runs:
+  using: composite
+  steps:
+    - name: Execute unit tests
+      shell: bash
+      run: |
+        qlt test run execute-unit-tests \
+          --num-threads "${{ inputs.num-threads }}" \
+          --language "${{ inputs.language }}" \
+          --runner-os "${{ runner.os }}" \
+          --work-dir "${{ inputs.work-dir }}" \
+          --base "${{ inputs.base }}" \
+          --automation-type actions \
+          ${{ inputs.codeql-args != '' && format('--codeql-args "{0}"', inputs.codeql-args) || '' }}
+
+    - name: Validate unit test results
+      shell: bash
+      run: |
+        # Deliberately omit --pretty-print: per QLT's own docs, that mode does not
+        # exit with a failure code on test failures, which we need for CI gating.
+        qlt test run validate-unit-tests \
+          --results-directory "${{ inputs.work-dir }}" \
+          --base "${{ inputs.base }}" \
+          --automation-type actions

.github/actions/save-qlt-cache/action.yml

@@ -0,0 +1,22 @@
+name: Save QLT cache
+description: |
+  Persists the cache directory populated by the `install-qlt` action (downloaded bundle and
+  compiled query artifacts) so subsequent runs can reuse it. Call this at the end of the job,
+  typically with `if: always()` so the cache is saved even if the test run failed.
+inputs:
+  cache-dir:
+    description: The cache directory output by the `install-qlt` action.
+    required: true
+
+  cache-primary-key:
+    description: The cache-primary-key output by the `install-qlt` action.
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - name: Save QLT cache
+      uses: actions/cache/save@v6
+      with:
+        path: ${{ inputs.cache-dir }}
+        key: ${{ inputs.cache-primary-key }}