Provide a Java view

[fbricon]

Lots of Java related extensions are contributing views to the side bar explorer these days: Maven, Java Dependencies, Tomcat, Spring boot dashboard... In the future, we will add a type hierarchy view once this is available in jdt.ls. This makes the regular explorer pretty crowded these days.

I think vscode-java should own a dedicated Java view, where companion extensions could contribute their stuff without bloating the explorer.
My only requirement is to not show that view if no view contributors are detected.

@gorkem @yaohaizh @akaroml @martinlippert WDYT?

[martinlippert]

Hey @fbricon, I share your concerns, it is getting pretty crowded for Java devs nowadays in VSCode with all those extensions. Not sure about the solution though, no good idea in mind. I usually like the quick in-place information boxes that people can show up in Eclipse via a simple keystroke, so they can stay in the editor all the time. For sounds tasty to me for something editor-centric like VSCode, too. Something like:

• keystroke, dialog shows up
• typing in stuff makes the outline show up, or the dependencies, or the tests, etc.

This could work well for type hierarchies, outlines, tests, and things like that. Might work less well for something like the boot dashboard or the java dependencies.

I know, more a few random thoughts instead of a well-thought-through concept, but that is what I have in mind at the moment.

[RuiffCardoso]

This would be good to improve debugging. Setting a debug point inside a dependency class is very hard. To resolve that issue, I normally just type that class name, so I can "Navigate into", but I found that a little hacky.

[jdneo]

@fbricon @rgrunber @testforstephen

I think this is exactly what we want right? microsoft/vscode#124031