curl: --help [option] displays documentation for given cmdline option

curl: --help [option] displays documentation for given cmdline option

Since the documentation text blob might be gzipped, it needs to search
for what to output in a streaming manner. It then first searches for
"\nALL OPTIONS".

Then, it looks for the start to display at "\n    -[option]" and stops
again at "\n    -". Except for the last option in the man page, which
ends at "\nFILES" - the subtitle for the section following all options
in the manpage.

Test 1707 to 1710 verify

Closes #13997