Refactor zsh completion function
Refactor zsh completion function

- Improve documentation
- Reorganise into functions
- Order options lexicographically
- Correct minor wording inconsistencies
- Fix --count error
- Fix --maxdepth error
- Fix --path-separator error
- Fix --version error
- Adjust exclusivity for --files, -h, -j, -o, -r, -t, -T, -v, -V, &c.
- Improve pattern-operand guard behaviour
- Partially fix issue with colorspec state
- Fix issue with typespec state
- Add completion for <type>:include: sequence
- Move licence info out of the way

BurntSushi/ripgrep,BurntSushi/ripgrep,BurntSushi/ripgrep,BurntSushi/ripgrep