Implement automatic release drafting

[Jomik]

Should allow us to make better use of the moonraker update channel.
Currently only maintains one draft, as release-drafter does not seem to be able to differentiate.
I will look into adding that functionality in their application, but this should at least help us get started.

With this change we can ask our users to set channel: beta and it should automatically use the tag of the newest published release.
To target the users on channel: stable we would have to mark a release as not pre-release and "latest".
channel: dev will, as now, pull latest commit from master - we should move the general users away from this.

Example: https://github.com/Jomik/release-drafter-test/releases

[krautech]

Looks good to me @RichardTHF I think we should implement it and work towards having this pipeline setup for better workflow and management.

Will have to test the channel: things though but thats not a direct impact initially.