Make "args": "${command:pickArgs}" as default debug configuration

[PRO-2684]

Originally posted at vscode/issues#225834

I was really frustrated when I "debug Python files with arguments", input my space-separated argument list, and see my script treating it like a single argument. So I think it is more sensible to make "args": "${command:pickArgs}" as default, instead of "args": ["${command:pickArgs}"]. More specifically, I suggest changing the default debug configuration:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python Debugger: Python File",
            "type": "debugpy",
            "request": "launch",
            "program": "${file}",
            "console": "integratedTerminal",
            "args": [
                "${command:pickArgs}"
            ]
        }
    ]
}

to:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python Debugger: Python File",
            "type": "debugpy",
            "request": "launch",
            "program": "${file}",
            "console": "integratedTerminal",
            "args": "${command:pickArgs}"
        }
    ]
}