Implement abstraction layer for the USB OTG module

[lucas-yotsui]

Tasks

For this issue to be considered completed, the following tasks must be fulfilled:

Implementation

• Map all the registers related to the USB OTG module.
• Implement functions for abstracting register access.
• Implement the USB protocol itself. Maybe not all of it, but the basics like the most common descriptors and all that.
  NOTE: Take some time to implement the USB protocol properly. It is extremely complex and will require some extra attention.

Documentation

• Document the role of each register.
• Document the role of each bit on each register.
• Document how to use all the functions.

Testing

• Write unit tests for all that can be tested in such a way
• Test the rest of the functionality manually and ensure everything works properly.