IDE integration for Xtc tracker

[lagergren]

Once we have a language aware build system, in our case, a gradle XTC plugin, and simplified the build to look like any other language build, based only on what we want done, and dependency, not explicitly telling the build system how to do it, we fulfil the fundamental requirements to put language integration with IDEs on top of that.

This is intended as an umbrella issue, that will be split up into subtasks, once we start implementing it

Some of them likely are:

• Eclipse / VS Code / other APIs than IntelliJ, seem to be standardising on language server APIs. Hence, it makes sens to write a language sever for xtc to be able to plug stuff like debugging into it.
• If possible, we can try to appropriate whatever language server plugins exist for IntelliJ too, so we only need this amount of code. The existing attempts of language servers for IntelliJ, however, are still very alpha, and quite limited. Part of the reason for that seems to be that IntelliJ is very different from other IDEs internally.
• IntelliJ integration requires the IntelliJ tooling API, and there is no mature language server, so we would likely have to have a unique implementation.
• Any language support like lexing, highlighting, auto-completion that is outside the language server scope. First task for dogfooding purposes would be to do this with the IntelliJ API as well.