[Feature] Configure scripts to run before and after a game is launched

[arielj]

This PR closes #2507. This can be used to change keyboard layout, screen resolution, or trigger any script the user wants to.

This PR adds 2 configuration options for games to set a script that would run before the game is launched, and one that would run after the game closes:

The code will wait for the script to exit before continuing with the launching of the game, so if something should run in the background in parallel to the game it must be handled by the script itself. For example, in bash:

#!/bin/bash

echo "this runs before the game" # this is sync
bash ./another-script.bash & # note the `&` at the end, this will run in parallel and finish when it needs to
echo "this also runs before the game" # this is sync too

With a file like this, Heroic will process the first and last line and proceed to launch the game. It will also process the second line but it won't wait for it to finish, so make sure the synchronous code exits and doesn't leave Heroic waiting forever.

Note that scripts are run in the context of the install directory of the game (working directory is set to the install_path of the game).

I only tested this on linux, so any feedback is welcomed, specially on windows.

I imagine the must will have to be accessible in the Flatpak's permissions if using Heroic flatpak.

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Use the following Checklist if you have changed something on the Backend or Frontend:

• Tested the feature and it's working on a current and clean install.
• Tested the main App features and they are still working on a current and clean install. (Login, Install, Play, Uninstall, Move games, etc.)
• Created / Updated Tests (If necessary)
• Created / Updated documentation (If necessary)

[flavioislima]

About the Settings itself, do you think would be better to do like this:

• Select Alt EXE
• Game Arguments
• New section called Scripts (similar to the wrapper command subtitle
• Select script to run before
• Select script to run after

I think would be more intuitive then having script before, exe, script after and then game arguments. Even though they are related, they do not serve the same purpose:

[arielj]

@flavioislima just pushed a change re-ordering them