Use host WINE to run rcedit

[Calinou]

This is required to make Changing application icon for Windows work from the Flatpak build of Godot.

Alternatively, we could bundle WINE and rcedit in the Flatpak, but this is a difficult task that also increases the bundle size quite a bit.

[belug23]

For those still looking for a solution to this problem here's how I just solved it.

The current version of the flatpack requires the filesystem:host permission this allows you to gain access to the system's executables, but they're in a different folder.

For my need I had to use /run/host/bin/wine64-stable the path /run/host/ is created in the sandbox by flatpack and give you access to the full filesystem.

[TaraSophieDev]

can this be added to the docs please? Flatpak is the most used app system on linux.

[Calinou]

can this be added to the docs please? Flatpak is the most used app system on linux.

I suggest opening a PR to modify this Flatpak's README, but as this Flatpak isn't officially supported, the Godot docs shouldn't include instructions for it.