Implement `verbose` toggle from godot repo

[Repiteo]

Brings over the verbose environment variable from the main godot repo. Much like the main repo, it's disabled by default & enabling it will output logs identical to how they currently output. By leaving verbosity disabled, the outputs are significantly trimmed down, which causes a very real performance boost in certain environments (eg: running the build command via a VSCode task). Verbosity is enabled for GitHub Actions, both to mirror the godot repo & because those should be giving explicit output.