Add support for pickProcess with remote debugging via platformInitCommands

[nkronlage]

I'd love to be able to use ${command:pickProcess} with remote debugging to Android but that currently did not work because the platform process list command issued by pickProcess does not let you specify the remote platform.

This is a proposal to have a "platformInitCommands" list that is used both in debugger setup and in pickProcess to let you select/connect the platform.

Here's an example of using `"pid": "${command:pickProcess}" when debugging on an Android emulator:

[vadimcn]

Good idea! However, I don't like the proliferation of extra options. Can you think of any reason initCommands can't be used for process picker?

[nkronlage]

That should be ok! Was worried about breaking people if they do something that doesn't work well with pickProcess in their initCommands. But pickProcess never really worked with remote stuff before so that shouldn't be a problem.