Ensure devs use the expected build/formatting/warning settings

[jonahgraham]

I'd also really appreciate if someone with more knowledge of Gradle and its integration with Eclipse could take a look at what's currently going on when importing the LSP4J projects into an Eclipse workspace via the Gradle Project Import Wizard. Personally, I find it rather strange that some Eclipse-specific files (namely, org.eclipse.buildship.core.prefs, org.eclipse.xtext.java.Java.prefs, org.eclipse.xtend.core.Xtend.prefs) are generated at this time, while others (currently, only org.eclipse.jdt.core.prefs, it seems) are not (cannot?).

As an alternative, I also think that we could just put all these .prefs files under version control rather than generating them with Gradle. (BTW, we already have org.eclipse.core.resources.prefs under version control.) A potential drawback I can see with this approach is that any changes to those .prefs files will need to be replicated across all projects. But there are only so many projects in LSP4J, so it should not be a problem, I guess.

Originally posted by @pisv in #923

In addition to what @pisv outlines above, I would like to see this apply to code style issues too.

[pisv]

+1 for having project-specific code formatting settings (obviously :-))

[jonahgraham]

This will be folded into #937 - it may or may not be a distinct commit as #937 is pretty all encompassing.