Add missing int→Variant conversions

[Repiteo]

Implements int8_t, uint8_t, int16_t, and uint16_t operations/constructors for Variant. This matches the implementation of the main repo (albeit using the stdint.h names), and allows binding methods that use these types as parameters/returns

[Repiteo]

Also added signed long and unsigned long behind a NEED_LONG_INT define like the main repo. Frankly, I don't know how imperative this was, as the define is only used in iOS builds which I don't even think GDExtension supports, but the other int types were being ported over anyway so might as well

[dsnopek]

Thanks! This makes sense to me

Also added signed long and unsigned long behind a NEED_LONG_INT define like the main repo. Frankly, I don't know how imperative this was, as the define is only used in iOS builds which I don't even think GDExtension supports, but the other int types were being ported over anyway so might as well

GDExtension does support iOS builds, however, we don't ever define NEED_LONG_INT in the godot-cpp build system. Looking at Godot's build system it's defining it on iOS with arm64, so we should probably update the build system here to do the same.

[dsnopek]

This will need a rebase after PR #1299 in order for tests to pass

[Repiteo]

Rebased the repo & updated the iOS build system to use NEED_LONG_INT! I've never built for iOS so I wouldn't know how to test the change, but I included the define where it would reasonably be expecting an arm64 architecture. Because of the added "universal" option, the check was tweaked to ensure it's explicitly not x86_64

[dsnopek]

Thanks! This looks good to me, but I'm also not very experienced with iOS.

@bruvzg Do the iOS bits make sense to you?

[dsnopek]

Thanks! This looks good to me :-)

[dsnopek]

Cherry-picking to 4.1 in #1373