Hot-reloading

[Klaim]

Provide the option to enable hot-reloading. This generates additional code and defines.

I intend to set this by on by default, although upstream they do it only for the "develop" build, which for them is the build they use to debug the tools. Not sure of the exact meaning and how to translate it to Godot.

Note that hot-reloading is only enabled starting Godot 4.2-dev6 so the option will be added for versions >= 4.2 only.

[Klaim]

I had to fix some bugs in the Godot side, but otherwise the hot-reloading works (once that version of godot 4.2-beta2 is published):

• https://github.com/godotengine/godot/pull/83260
• https://github.com/godotengine/godot/pull/83285

[Klaim]

Only thing missing: there seems to be an issue with setting the option.

[Klaim]

Godot v4.2 is now published and I tagged a version, which enables hot-reloading by default.

Still didnt fix the hot-reloading option for now.

[Klaim]

I believe this issue is what I was seeing that prevented me from closing this: https://github.com/build2/build2/issues/356

[Klaim]

I'll close this issue as the feature works but is just made harder to use by https://github.com/build2/build2/issues/356 although it can be worked around.