Process colorSchemeSimulation in TargetConfigurationActor (#36297)

Implements Steps 1,4&6 of https://github.com/servo/servo/issues/35867:
- Adds `pub simulate_color_scheme` to `BrowsingContextActor` using
`script_chan`.
- Processes `colorSchemeSimulation` flag in `TargetConfigurationActor`’s
`updateConfiguration`.
- Routes `colorSchemeSimulation` from `RootActor` via
`TabDescriptorActor` to `BrowsingContextActor`.

Testing: Compiles and lints clean.
Fixes: https://github.com/servo/servo/issues/35867

---------

Signed-off-by: Uthman Yahaya Baba <uthmanyahayababa@gmail.com>

components/devtools/actors/browsing_context.rs

@@ -11,8 +11,11 @@ use std::collections::HashMap;
 use std::net::TcpStream;
 
 use base::id::PipelineId;
-use devtools_traits::DevtoolScriptControlMsg::{self, GetCssDatabase, WantsLiveNotifications};
+use devtools_traits::DevtoolScriptControlMsg::{
+    self, GetCssDatabase, SimulateColorScheme, WantsLiveNotifications,
+};
 use devtools_traits::{DevtoolsPageInfo, NavigationState};
+use embedder_traits::Theme;
 use ipc_channel::ipc::{self, IpcSender};
 use serde::Serialize;
 use serde_json::{Map, Value};
@@ -352,4 +355,10 @@ impl BrowsingContextActor {
             let _ = stream.write_json_packet(&msg);
         }
     }
+
+    pub fn simulate_color_scheme(&self, theme: Theme) -> Result<(), ()> {
+        self.script_chan
+            .send(SimulateColorScheme(self.active_pipeline_id.get(), theme))
+            .map_err(|_| ())
+    }
 }