Rename namespace dawn_wire to dawn::wire.

But keep a namespace alias to avoid breaking project that depend on the
previous namespace name while they get updated.

Bug: dawn:824
Change-Id: I1e99c4d0d2acf7644a225a88d07806d1a64478e6
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/75540
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>

src/dawn_wire/client/ObjectBase.h

@@ -20,7 +20,7 @@
 #include "common/LinkedList.h"
 #include "dawn_wire/ObjectType_autogen.h"
 
-namespace dawn_wire::client {
+namespace dawn::wire::client {
 
     class Client;
 
@@ -46,6 +46,6 @@ namespace dawn_wire::client {
         const uint32_t id;
     };
 
-}  // namespace dawn_wire::client
+}  // namespace dawn::wire::client
 
 #endif  // DAWNWIRE_CLIENT_OBJECTBASE_H_