Get rubber-ducky example working with new descriptor features.

[antoinevg]

This PR does a bunch of things:

• There is some ancient confusion in bits of the codebase when referring to a descriptor's number and type_number. The number is the descriptor number whereas type_number is the descriptor type. This was causing identifier lookups to fail when searching for a descriptor in requestable_descriptors.
• The Keyboard device's HIDDescriptor also needed to specify include_in_config.
• The data class for USBClassDescriptor needed a type annotation.

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closes #133

[jalmeroth]

I just deleted my other comment from before…

I realized that include_in_config: bool = True must be typed with bool to actually be considered. :see_no_evil: include_in_config = True is not enough.