IPC is now its own HostInputType and doesn't get swallowed

[SetsukiFR]

This is my very first pull request on GitHub ever. I apologize if I didn't respect an etiquette or did this incorrectly.

Goal

Make IPC inputs function even when EmuHawk doesn't have focus, without requiring setting the 'listen to input even when in background' setting.

I made this originally for a custom "TwitchPlays" plugin. What I needed was for EmuHawk to listen to input from another process running, while in the background, and not listening to keyboard inputs (keyboard was being used by the streamer during the live).

How

I added a new HostInputType for IPC, and separated the way these inputs are processed from regular keyboard controls.

Potential issues

1. My main doubt is in Input.cs ShouldSwallow(), where I made IPC being swallowed under NO circumstances.

2. I wasn't sure wether to

set the value of HostInputType.IPC to 8
replace the value of HostInputType.Ignore from 8 to 16

or, what I did

set the value of HostInputType.IPC to 16

No AI

No AI tools have been used for this (plus it's pretty simple)I hope this'll come in handy!
Thank you so much for your work and have a nice day!