Reorganize v8 contexts and scope

- Pages within the same session have proper isolation
  - they have their own window
  - they have their own SessionState
  - they have their own v8.Context

- Move inspector to CDP browser context
  - Browser now knows nothing about the inspector

- Use notification to emit a context-created message
  - This is still a bit hacky, but again, it decouples browser from CDP

src/cdp/domains/runtime.zig

@@ -44,10 +44,7 @@ fn sendInspector(cmd: anytype, action: anytype) !void {
     const bc = cmd.browser_context orelse return error.BrowserContextNotLoaded;
 
     // the result to return is handled directly by the inspector.
-    bc.session.callInspector(cmd.input.json);
-
-    // force running micro tasks after send input to the inspector.
-    cmd.cdp.browser.runMicrotasks();
+    bc.callInspector(cmd.input.json);
 }
 
 fn logInspector(cmd: anytype, action: anytype) !void {