fix: runcommand with args fails on windows

Summary

This is a fix for plugin Run commands. On windows, it cannot run command with args. This patch prefixs cmd /C to the user command.

Tested ok with this binary(https://invent.kde.org/yebenny/kdeconnect-kde/-/jobs/1898623/artifacts/download).

Test Plan

Add following command in the Run commands plugin:

explorer C:\Windows

Trigger the command on the phone.

Before:

The command fails.

After:

Open file explorer in C:\Windows