add github release based trigger

[mpmxyz]

requires #35
Possible chain of actions would be:

1. optional: manual OR tag trigger
   1a. create github release draft
   OR
   1b. update release draft and trigger next step if manual has "override" and release draft already exists
2. on created release draft or trigger from previous step (verify version format first!)
   2a. RML compile/test
   2b. MonkeyLoader compile/test
3. after compilation/tests are finished
   3a. RML
   3a.1. add artifacts to release
   3a.2. amend RML manifest
   3b. MonkeyLoader
   3b.1. push nuget package
4. make release public

Problem with that approach: github release will be created before code is compiled/tested.