Add option --resolve

[fabricereix]

Add curl option --resolve
(https://curl.se/docs/manpage.html#--resolve)

[JanKoppe]

This would be a pretty great feature! We're currently trying to use Hurl to test an elaborate Caddy configuration locally before rolling it out, and it would be awesome if we could just resolve all the hundreds of hostnames in that case to localhost instead to point it to the test-instance of Caddy.

Currently I'm struggling to find an alternative way to do this.

[jcamiel]

Noted, we can try to prioritise this issue because there is no real difficulties (the core of the work is delegated to libcurl).

[jcamiel]

@JanKoppe just added the --resolve option on master. You can build Hurl if you want to have it now, or wait a little, we plan to release a new version at the beginning of January.