devtools: Fix id collisions by using incrementing counters (#35971)

Devtools clients need a `browserId`, `browsingContextID`, and
`outerWindowID`, which correspond to WebViewId, BrowsingContextId, and
PipelineId in Servo. These u32 values were previously derived from our
sharded (u32,u32) id values by taking only the `index` (second u32) and
ignoring the `namespace_id` (first u32), leading to collisions.

This patch fixes that by mapping those Servo ids to sequential u32
values.

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---------

Signed-off-by: Delan Azabani <dazabani@igalia.com>

components/devtools/actors/console.rs

@@ -152,7 +152,7 @@ impl ConsoleActor {
             Root::BrowsingContext(bc) => UniqueId::Pipeline(
                 registry
                     .find::<BrowsingContextActor>(bc)
-                    .active_pipeline
+                    .active_pipeline_id
                     .get(),
             ),
             Root::DedicatedWorker(w) => UniqueId::Worker(registry.find::<WorkerActor>(w).worker_id),