refactor: use include syntax for wasi:clocks

This commit uses `include` syntax to simplify the proxy world
by hiding the interfaces from wasi:clock package

Signed-off-by: Jiaxiao Zhou (Mossaka) <duibao55328@gmail.com>

wit/proxy.wit

@@ -1,15 +1,13 @@
-package wasi:http;
+package wasi:http
 
 /// The `wasi:http/proxy` world captures a widely-implementable intersection of
 /// hosts that includes HTTP forward and reverse proxies. Components targeting
 /// this world may concurrently stream in and out any number of incoming and
 /// outgoing HTTP requests.
 world proxy {
-  /// HTTP proxies have access to time and randomness.
-  import wasi:clocks/wall-clock;
-  import wasi:clocks/monotonic-clock;
-  import wasi:clocks/timezone;
-  import wasi:random/random;
+  // HTTP proxies have access to time and randomness.
+  include wasi:clocks/imports
+  import wasi:random/random
 
   /// Proxies have standard output and error streams which are expected to
   /// terminate in a developer-facing console provided by the host.