Refactor ide independent stuff into an ide plugin

[soerendomroes]

No description provided.

[sailingKieler]

The new plugin's stuff is only consumed by the ...ui.view plugin, right?
Is it intended to be used in non-Eclipse-based IDEs? Might make sense to add an derived version of https://github.com/kieler/KLighD/blob/master/plugins/de.cau.cs.kieler.klighd.standalone/src/de/cau/cs/kieler/klighd/standalone/KlighdStandaloneSetup.java, doesn't it?

[soerendomroes]

The main idea was to make the syntheses and stuff like the MessageModel available for setups that do not want to consume the ui plugins. I think a StandaloneSetup is orthogonal to this issue.
I suggest to add one if the need arises or is there already one @NiklasRentzCAU ?
This refactoring is a first step to do the same for the KIELER semantics bundles.

[sailingKieler]

I'm fine with the additions & moves.

[NiklasRentzCAU]

Also looks good to me.
There is no derived version of the standalone setup yet, I don't see that we need one anyway. The language server setup in the keith branch will need that, but is not fully implemented over there yet. If we see something that needs to be added to the ide plugin, we'll do it then.

[NiklasRentzCAU]

Please have a look at the failed PR-build over here first, though.
Can't we add a way to include the build status of these PR builds on GitHub? I think I saw something like that over at other repositories already.

[soerendomroes]

The PR build seems to be successful now.

[uruuru]

@NiklasRentzCAU I guess you refer to github actions. Have a look at this config, should only require small adjustemts: https://github.com/eclipse/elk/blob/master/.github/workflows/ci.yml