feat: export cli runner and add documentation for use-case (#1040)

* chore: bump dorny/test-reporter from 1.5.0 to 1.6.0 (#1037)

Bumps [dorny/test-reporter](https://github.com/dorny/test-reporter) from 1.5.0 to 1.6.0.
- [Release notes](https://github.com/dorny/test-reporter/releases)
- [Changelog](https://github.com/dorny/test-reporter/blob/main/CHANGELOG.md)
- [Commits](dorny/test-reporter@v1.5.0...v1.6.0)

---
updated-dependencies:
- dependency-name: dorny/test-reporter
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* feat: export cli runner and add documentation for use-case

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: incendial

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 
+* feat: make CliRunner a part of public API in order to support transitive executable calls use-case.
 * feat: add static code diagnostic [`avoid-cascade-after-if-null`](https://dartcodemetrics.dev/docs/rules/common/avoid-cascade-after-if-null).
 
 ## 4.21.2

lib/cli_runner.dart

@@ -0,0 +1 @@
+export 'package:dart_code_metrics/src/cli/cli_runner.dart';

website/docs/cli/index.md

@@ -60,3 +60,17 @@ metrics:
     Run `dart_code_metrics` in all packages.
      - Note: you can also rely on your IDEs Dart Analysis / Issues window.
 ```
+
+## Calling the cli from your own package with the linter configuration
+
+If you have a separate package with all the linter and DCM configurations which is used by your other packages and you want to call DCM transitively add a `bin` folder with a Dart file, for example
+
+```dart metrics.dart
+import 'package:dart_code_metrics/cli_runner.dart';
+
+Future<void> main(List<String> args) async {
+  await CliRunner().run(args);
+}
+```
+
+After that you will be able to run DCM by calling your package executable.