noproxy: support proxies specified using cidr notation

For both IPv4 and IPv6 addresses. Now also checks IPv6 addresses "correctly"
and not with string comparisons.

Split out the noproxy checks and functionality into noproxy.c

Added unit test 1614 to verify checking functions.

Reported-by: Mathieu Carbonneaux

Fixes #9773
Fixes #5745
Closes #9775

docs/KNOWN_BUGS

@@ -119,7 +119,6 @@ problems may have been fixed or changed somewhat since this was written.
  11.9 DoH does not inherit all transfer options
  11.10 Blocking socket operations in non-blocking API
  11.11 A shared connection cache is not thread-safe
- 11.12 'no_proxy' string-matches IPv6 numerical addresses
  11.14 Multi perform hangs waiting for threaded resolver
  11.15 CURLOPT_OPENSOCKETPAIRFUNCTION is missing
  11.16 libcurl uses renames instead of locking for atomic operations
@@ -931,13 +930,6 @@ problems may have been fixed or changed somewhat since this was written.
 
  See https://github.com/curl/curl/issues/4915 and lib1541.c
 
-11.12 'no_proxy' string-matches IPv6 numerical addresses
-
- This has the downside that "::1" for example does not match "::0:1" even
- though they are in fact the same address.
-
- See https://github.com/curl/curl/issues/5745
-
 11.14 Multi perform hangs waiting for threaded resolver
 
  If a threaded resolver takes a long time to complete, libcurl can be blocked

docs/libcurl/opts/CURLOPT_NOPROXY.3

@@ -53,10 +53,6 @@ brackets:
 
  "example.com,::1,localhost"
 
-IPv6 numerical addresses are compared as strings, so they will only match if
-the representations are the same: "::1" is the same as "::0:1" but they do not
-match.
-
 The application does not have to keep the string around after setting this
 option.
 .SH "Environment variables"