ci: tune cpp-linter to use repo style and reduce PR noise (#297)

Configure the `cpp-linter` workflow to read formatting rules from the
repository and make its PR feedback less noisy.

This makes the formatting source of truth live in the repository instead
of being hard-coded in the workflow, which gives us a cleaner path to
adjust style over time.

It also shifts `cpp-linter` feedback away from noisy PR comment churn
and toward the GitHub Actions UI, while still failing the job when
checks fail.

Author: plexoos

.clang-format

@@ -0,0 +1 @@
+BasedOnStyle: Microsoft

.github/workflows/build-pull-request.yaml

@@ -29,12 +29,15 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
-          style: microsoft
+          style: file
           ignore: include/argparse
           lines-changed-only: true
           thread-comments: update
-          format-review: true
+          format-review: false
           tidy-checks: '-*'
+          tidy-review: false
+          step-summary: true
+          file-annotations: true
 
       - name: Fail fast?!
         if: steps.linter.outputs.checks-failed != 0