Automatically remap endpoint addresses based on their capabilities

[xairy]

Right now, USB Proxy tried to use the same addresses for UDC endpoints as the addresses that are provided in the USB descriptors of the proxied device. This doesn't always work, as UDC endpoints might not support the required addresses or capabilities.

Instead, we need to dynamically remap the endpoint addresses; see assign_ep_address in the Raw Gadget examples for reference.

This issue has previously came up here.