plugins/proclist: Implement a full-php way to get process list in Linux

[nil0x42]

Current implementation of proclist plugin uses win32_ps_list_procs() php function on Windows host.

Therefore, linux implementation is a simple system("ps -a"), which is OPSEC unsafe, an would probably trigger EDR alerts.

A better implementation should avoid relying on system command execution.

[paralax]

would groveling through /proc on linux work, you think?

[nil0x42]

i think it's a lot better indeed @paralax ! anyway ps does that internally, directly reading on /proc is probably the best way