Execute remote system commands with output capture `:!!`

[trufae]

Implement :! command to run commands and capture the output and print it to the host side

[trufae]

right now this is implemented in src/agent/lib/debug/system.ts. which handles the :! command. but we need to have the :!! which captures the output and prints it to host side. we can do this with popen or redirecting the stdout fd before system, etc.