Add support for enums with custom integer types

[BHolman-LBI]

Describe the bug
Unsure if this is a bug or a feature request:

The following snippet compiles and triggers a heap corruption runtime check on MSVC

enum class ETest : uint8_t
{
    A, B
};
int main()
{
    
    flecs::world ecs;

    ecs.component<ETest>();
    ecs.entity().set<ETest>(1);
    return 0;
}

Expected behavior
I don't think the above should be allowed to compile?

[SanderMertens]

Updated the description, this is not currently supported. Will look into why it crashes though, that's not nice.

[SanderMertens]

Added an assert that checks if the enum is of the correct size.