Add github action for automation

[Chris2011]

It would be good, if we can have a github action to automate some things. For example making a release after merging to master for github. Next step would be to make a NBM file and make a release to maven and to the plugin portal.

[javierllorente]

Good idea.
AFAIK, there is no API for doing some things in the plugin portal, like adding NB releases to a plugin version, requesting verification for NB releases. But the rest could be automated. I would do it based on tagging a netbeans-rest-client release.

[Chris2011]

Sure, but at the end, we could try to reverse engineer the API to check what are they doing. But this is a nice to have :). Priop would be bring the stuff as a release to github and maybe to maven.