Rework Documentation

[spacecheese]

• [x] Rewrite static documentation.
• [x] Fixes for main README.md
• [x] Include README.md in index (instead of having two main pages).
• [x] Change to Furo theme
• [x] Add black source formatting check
• [x] Add autogen rule for api reference
• [x] Rename some internal functions to start with _ (so they don't show up in docs)
• [x] Add some test improvements relating to the UUID16 refactor
• [x] Links https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/ should reference a tag (structure of documentation has changed post 5.70 release and broken links)
• [x] Include links to relevant source code
• [x] Add type hint checking
• [x] characteristic.py type annotations
• [x] descriptor.py type annotations
• [x] Error docstrings (and fix references to using the bluez error strings directly)
• [x] Other missing docstrings
• [x] More complete testing for UUID changes
• [x] Fix https://github.com/spacecheese/bluez_peripheral/issues/46
• [x] Remove references to internal class members

[spacecheese]

~~Merge after #23~~