Autogenerated documentation for supported VT sequences

[christianparpart]

Just like the terminfo file can be auto-generated, or the VT parser FSM, it is also possible to auto-generate the list of supported VT sequences along with some additional info (might require adding more metadata but that's okay).

• [x] expose list of supported VT sequences via CLI
• [ ] maybe support different formats? At least markdown? txt? man-page (groff)?

VT sequence meta data

• [x] mnemonic
• [x] VT syntax
• [x] short description
• [ ] maybe a longer one?
• [ ] category tag(s) - such as "cursor placement", "rectangular"
• [x] VT level or extension
• [ ] additional notes?