Allow manual configuration of the editor settings file location

[1player]

This function:

https://github.com/godotengine/emacs-gdscript-mode/blob/5136be407a3479ad1fb944acdd36b065833f48f6/gdscript-eglot.el#L45

hardcodes a few locations to find the godot settings file, with no way to overwrite it. For example, on Linux I use the "Godots" flatpak which doubles as a version manager for godot, and the editor settings file is at .var/app/io.github.MakovWait.Godots/config/godot/ rather than under ~/.config/godot.

Please allow a user to manually specify the location of this file. Right now for my use case a terrible workaround is to copy or symlink the file into ~/.config/godot for eglot LSP to work.