(DAP) Arbitrary command execution

As I understand it, when I type something into the entry field/bar at the bottom of vscode's debugger pane, that is sent to delve as an evaluation request. AFAIK this supports one 'command': call.

I propose adding support for arbitrary command execution: If the string to be evaluated is prefixed with >, the input is treated as a command and processed in the same way dlv cli commands would be processed. For example this would help enable multiprocess debugging by adding support for executing > target follow-exec -on (#3947).