Add URL struct

Combine uri + rawuri into single struct.

Try to improve ownership around URIs and URI-like things.
 - cookie & request can take *const std.Uri
   (TODO: make them aware of the new URL struct?)
 - Location (web api) should own its URL (web api URL)
 - Window should own its Location

Most of these changes result in (a) a cleaner Page and (b) not having to carry
around 2 nullable objects (URI and rawuri).

src/cdp/domains/input.zig

@@ -64,11 +64,7 @@ fn dispatchMouseEvent(cmd: anytype) !void {
             else => unreachable,
         },
     };
-    const click_result = (try page.mouseEvent(cmd.arena, mouse_event)) orelse return;
-
-    switch (click_result) {
-        .navigate => |uri| try clickNavigate(cmd, uri),
-    }
+    try page.mouseEvent(mouse_event);
     // result already sent
 }