allows sendmmsg api taking owned values (as well as references) (#18999)

Current signature of api in sendmmsg requires a slice of inner
references:
https://github.com/solana-labs/solana/blob/fe1ee4980/streamer/src/sendmmsg.rs#L130-L152

That forces the call-site to convert owned values to references even
though doing so is redundant and adds an extra level of indirection:
https://github.com/solana-labs/solana/blob/fe1ee4980/core/src/repair_service.rs#L291

This commit expands the api using AsRef and Borrow traits to allow
calling the method with owned values (as well as references like
before).

gossip/src/cluster_info.rs

@@ -1250,13 +1250,13 @@ impl ClusterInfo {
         let dests: Vec<_> = if forwarded {
             peers
                 .iter()
-                .map(|peer| &peer.tvu_forwards)
+                .map(|peer| peer.tvu_forwards)
                 .filter(|addr| ContactInfo::is_valid_address(addr, socket_addr_space))
                 .collect()
         } else {
             peers
                 .iter()
-                .map(|peer| &peer.tvu)
+                .map(|peer| peer.tvu)
                 .filter(|addr| socket_addr_space.check(addr))
                 .collect()
         };