client/remote: add support to specify port number

this adds the ability to add port numbers in the backup repo spec
as well as remotes, so that user that are behind a
NAT/Firewall/Reverse proxy can still use it

also adds some explanation and examples to the docs to make it clearer
for h2 client i left the localhost:8007 part, since it is not
configurable where we bind to

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

src/client/pull.rs

@@ -439,7 +439,7 @@ pub async fn pull_group(
             .password(Some(auth_info.ticket.clone()))
             .fingerprint(fingerprint.clone());
 
-        let new_client = HttpClient::new(src_repo.host(), src_repo.user(), options)?;
+        let new_client = HttpClient::new(src_repo.host(), src_repo.port(), src_repo.user(), options)?;
 
         let reader = BackupReader::start(
             new_client,