Emit networkIdle and networkAlmostIdle Page.lifecycleEvent

Most CDP drivers have a mechanism to wait for idle network, or an almost idle
network (sometimes called networkIdle2). These are events the browser must emit.

The page will now emit `networkIdle` when we are reasonably sure there's no more
network activity (this requires some slight changes to request interception,
since, I believe, intercepted requests should be considered).

`networkAlmostIdle` is currently _always_ emitted prior to emitting
`networkIdle`. We should tweak this but I can't, at a glance, think of a great
heuristic for when this should be emitted.

src/cdp/domains/page.zig

@@ -78,12 +78,16 @@ fn getFrameTree(cmd: anytype) !void {
 }
 
 fn setLifecycleEventsEnabled(cmd: anytype) !void {
-    // const params = (try cmd.params(struct {
-    //     enabled: bool,
-    // })) orelse return error.InvalidParams;
+    const params = (try cmd.params(struct {
+        enabled: bool,
+    })) orelse return error.InvalidParams;
 
     const bc = cmd.browser_context orelse return error.BrowserContextNotLoaded;
-    bc.page_life_cycle_events = true;
+    if (params.enabled) {
+        try bc.lifecycleEventsEnable();
+    } else {
+        bc.lifecycleEventsDisable();
+    }
     return cmd.sendResult(null, .{});
 }
 
@@ -357,6 +361,27 @@ pub fn pageNavigated(bc: anytype, event: *const Notification.PageNavigated) !voi
     }, .{ .session_id = session_id });
 }
 
+pub fn pageNetworkIdle(bc: anytype, event: *const Notification.PageNetworkIdle) !void {
+    return sendPageLifecycle(bc, "networkIdle", event.timestamp);
+}
+
+pub fn pageNetworkAlmostIdle(bc: anytype, event: *const Notification.PageNetworkAlmostIdle) !void {
+    return sendPageLifecycle(bc, "networkAlmostIdle", event.timestamp);
+}
+
+fn sendPageLifecycle(bc: anytype, name: []const u8, timestamp: u32) !void {
+    const loader_id = bc.loader_id;
+    const target_id = bc.target_id orelse unreachable;
+    const session_id = bc.session_id orelse unreachable;
+
+    return bc.cdp.sendEvent("Page.lifecycleEvent", LifecycleEvent{
+        .name = name,
+        .frameId = target_id,
+        .loaderId = loader_id,
+        .timestamp = timestamp,
+    }, .{ .session_id = session_id });
+}
+
 const LifecycleEvent = struct {
     frameId: []const u8,
     loaderId: ?[]const u8,