New Hydradancer backend for Facedancer

[kauwua]

Here are some characteristics and results of this backend, which I think would make it a good addition to this project:

• supports USB2 High-speed, Full-speed and should support low-speed
• 6 endpoints including EP0, in both IN/OUT directions simultaneously
• endpoint numbers from 0 to 7
• increased speed compared to Facedancer21/GreatFET One, results here https://github.com/HydraDancer/hydradancer_fw
• support for NAKs, but also priming using handle_buffer_empty
• tested emulation of a mouse peripheral and the included mass storage example
• tested proxy mode with a High-speed USB key (got 1.5MB transfer rate while proxying a 1.5GB file), tested proxy mode with a Full-speed mouse