[Feature] Support for mangohud flatpak

[Heus-Sueh]

govelay only detects mangohud in .deb .rpm format, it would be interesting if it supports flatpak as well

[binarydepth]

+1

[benjamimgois]

Hey guys, i know... Flatpak still a kind of a blackbox to me. I still plan to make it happen, just lacking time lately.

[csc-chicken]

I tried to build myself in gnome builder in order to build a flatpak to test, but I faced link error

/home/leon/文件/goverlay-git/goverlay/goverlay.lpr(27,1) Error: (9013) Error while linking
/home/leon/文件/goverlay-git/goverlay/goverlay.lpr(27,1) Fatal: (10026) There were 1 errors compiling module, stopping
Fatal: (1018) Compilation aborted
Error: /usr/bin/ppcx64 returned an error exitcode
Error: (lazarus) Compile Project, Mode: Release, Target: goverlay: stopped with exit code 1
Error: (lazbuild) failed compiling of project /home/leon/文件/goverlay-git/goverlay/goverlay.lpi

google it maybe It's the Lazarus update cause this problem. If it is solved, gnome builder make dev easy to build a flatpak image