Before:
* hand write arg parse
* only accepts one suffix
After:
* use `arg_parse` to parse args
* accepts multi suffixes
Closes#9611.
(cherry picked from commit aa65856ee009d3484c4dcc3d81aceb781810b8f6)
Just a bunch of rewriting descriptions and some arguments.
Most arguments here are uncompleteable, and most of these options will
never be used.
[ci skip]
Allows the most painful of curl's arguments to be completed by fish by
restoring file-based completions for paths prefixed with `@` (which are
typically used after parameters like --data).