Make std.net.socket.SocketAddress an inline type

This removes the need for a heap allocation when getting IP socket
addresses.

Changelog: performance

std/src/std/net/socket.inko

@@ -86,7 +86,7 @@ trait RawSocketOperations {
 }
 
 # An IPv4 or IPv6 socket address.
-class pub SocketAddress {
+class pub inline SocketAddress {
   # The IPv4/IPv6 address of this socket address.
   let pub @ip: IpAddress
 
@@ -96,7 +96,7 @@ class pub SocketAddress {
 
 impl Equal[ref SocketAddress] for SocketAddress {
   # Returns `true` if `self` and `other` are the same.
-  fn pub ==(other: ref SocketAddress) -> Bool {
+  fn pub inline ==(other: ref SocketAddress) -> Bool {
     @ip == other.ip and @port == other.port
   }
 }