Use client agnostic command names

From https://github.com/eclipse/eclipse.jdt.ls/pull/424#issuecomment-344130840, I noticed the debugger exposes vscode* commands on the server side.

[Trace - 21:52:28] Received request 'client/registerCapability - (5)'.
Params: {
    "registrations": [
        {
            "id": "18163e21-97e7-4ae8-b51c-5cdb20e639b1",
            "method": "workspace/executeCommand",
            "registerOptions": {
                "commands": [
                    "java.edit.organizeImports",
                    "vscode.java.fetchUsageData",
                    "vscode.java.resolveClasspath",
                    "vscode.java.resolveMainClass",
                    "vscode.java.updateDebugSettings",
                    "vscode.java.buildWorkspace",
                    "vscode.java.startDebugSession"
                ]
            }
        }
    ]

It'd be better if the names were client agnostic.

Start by locating where the listed workspace/executeCommand names are registered and used, including the vscode.java.* commands shown in the issue. Determine the project's client-neutral naming convention, update the registrations and references consistently, and verify that command registration still works for the Java debug server.