[feature request] add the ability to send signals to attached program

[PartyWumpus]

(would require import signal, but it's an inbuilt package so no worries)

os.kill(pid, signal) can send a signal (signal.SIGSTOP for example) to any application. (ignore the name, it can do things other than kill)

A list of valid signals to select from can be generated with signal.valid_signals() (it produces a set of Signals, which have a value which is the number of the signal (19, 20, etc), a name which is the signal name (SIGCONT, SIGKILL, etc).
The set also includes a bunch of ints (on my PC, 35-63) that do not have any associated function, these should probably just be skipped. (64 does have a use on my PC)

for reference, all of these work (where 99 is the PID): os.kill(99, signal.SIGSTOP), os.kill(99, signal.SIGSTOP.value) and os.kill(99, 19).
these will NOT work: os.kill(99, "SIGSTOP") and os.kill(99, signal.SIGSTOP.name)

I would think a dropdown menu with every valid signal (by name, not number) and a "send" button next to it would be good.

I considered making this a seperate plugin, but it's not very complex and also fits pretty well into the functionality of this plugin.
I will try work on a PR myself (and may fail, we'll see) if you'd like, but I would prefer to hear some feedback (or if you'd like to do it) before I try.

Quick example code for getting a dictionary of signals:

import signal

valid_signals = signal.valid_signals()  # returns a set of objects, not particularly useful until parsed as needed

signals = {}
for sig in valid_signals:
    if hasattr(sig, "name") and hasattr(sig, "value"): # makes sure to ignore useless signals
        signals[sig.name] = sig.value
print(signals) # prints {'SIGHUP': 1, 'SIGINT': 2, 'SIGQUIT': 3...

Example code for pausing an application then instantly starting it again

import signal
import os

pid = 26724  # some int
os.kill(pid, signal.SIGSTOP)  # pause application
os.kill(pid, 18)  # continue application

code does not work from within flatpak vscode, probably due to sandboxing
works fine otherwise

[HeyItsWaters]

@PartyWumpus Can you briefly describe the benefits of adding something like this to the memory-deck plugin?

Technically speaking it seems pretty simple to add, just wondering if it would benefit the plugin itself.