Fix debug printing for dynamic types

[Davier]

Objective

Printing DynamicStruct with a debug format does not show the contained type anymore. For instance, in examples/reflection/reflection.rs, adding dbg!(&reflect_value); to line 96 will print:

[examples/reflection/reflection.rs:96] &reflect_value = DynamicStruct(bevy_reflect::DynamicStruct {
    a: 4,
    nested: DynamicStruct(bevy_reflect::DynamicStruct {
        b: 8,
    }),
})

Solution

Show the represented type instead (reflection::Foo and reflection::Bar in this case):

[examples/reflection/reflection.rs:96] &reflect_value = DynamicStruct(reflection::Foo {
    a: 4,
    nested: DynamicStruct(reflection::Bar {
        b: 8,
    }),
})

[MrGVSV]

I’m going to guess all of the dynamic types are broken in this way. Could we fix all of them in this PR as well? If not, we can tackle it in another PR.

[MrGVSV]

Might also be worth adding tests to ensure our Debug output doesn't break in the future.

[Davier]

I rebased to resolve merge conflicts.