Improve a GH action that publishes plugin registry on GH pages

We have a GH action that publishes plugins on GH page: https://github.com/redhat-developer/devspaces/actions/workflows/plugin-registry-build-publish-content-gh-pages.yaml

Sometimes this action doesn't publish last changes that was committed in the repository, to avoid such problems we can extend existing action by adding:

• make it possible to run the action manually (it should be possible to choose a branch)
• configure the action to be run periodically once a day for devspaces-3-rhel-8 branch