Add publish workflow

[Vladyslav-Kuksiuk]

It is necessary to add automatic plugin versions publishing.

See example.

Before publishing it is necessary to:

1. Generate API key and secret on the Gradle Plugin Portal.
2. Validate plugin:

   ./gradlew :gradle-plugin:publishPlugins --validate-only

3. Publish plugin:

   ./gradlew :gradle-plugin:publishPlugins

4. Wait to pass manual Portal review.