Add environment variables

[gernhan]

Add environment variables

[mfussenegger]

java-debug supports a env property in the configuration.

See https://github.com/microsoft/vscode-java-debug#options

E.g. with a launch.json file:

{
   "version": "0.2.0",
   "configurations": [
       {
           "type": "java",
           "request": "launch",
           "name": "Launch",
           "mainClass": "jdtlsdemo.App",
           "console": "integratedTerminal",
           "env": {
             "FOO": "yes"
           }
       }
   ]
}

And the App:

package jdtlsdemo;

public class App {

    public static void main(String[] args) {
        System.out.println(System.getenv("FOO"));
    }
}