WIP maintenance: improve ease of use in ref to issue #32

[UnlegitSenpaii]

attempt at improving usability with a script as described in issue #32

replaced my little testing script with it as its basically a better verion of it.

to disable the patch you now just need to remove the launch option, instead of checking the integrity of the files.

in recent light of issues with github repos being compromised, I'm not sure about automatic pulling. I need to think about it for a little longer before pushing this to master.

its possible to control the update functionality with the following variable in the run script:

#   prompt      — ask each time (default, recommended)
#   keep        — always use the existing binary without asking
#   auto-update — always pull and rebuild from GitHub without asking
FAE_UPDATE_MODE="prompt"

example launch option would be:
bash /home/admin/.local/share/Steam/steamapps/common/Factorio/fae_launch.sh %command%

feedback and help testing appreciated

[UnlegitSenpaii]

todo: create a wiki article with detailed, step by step, setup instructions for the steamdeck and linux enviroments.
maybe even a gif?