Desktop: Isolate CEF-rendered UI into separate crate and process (#4321)

* Extract CEF rendered UI into a separate process and crate

* Review

* Review

* Review

* Review

* Remove necessary workarounds

* Block on frame copy ack

* Crop and resample frames correctly

* Skip blank frames

* Fix deps

* Fix fmt

* Fix clippy warning

* Review

* Fix todo

desktop/ui/src/frames/sink.rs

@@ -0,0 +1,45 @@
+use ipc_channel::ipc::IpcSender;
+use std::sync::Mutex;
+
+use crate::remote::messages::HostControlMessage;
+
+pub(super) struct FrameSink {
+	state: Mutex<FrameSinkState>,
+}
+
+#[derive(Default)]
+struct FrameSinkState {
+	newest_installed: u64,
+	last_acked: u64,
+}
+
+impl FrameSink {
+	pub(super) fn new() -> Self {
+		Self {
+			state: Mutex::new(FrameSinkState::default()),
+		}
+	}
+
+	pub(super) fn deliver(&self, sender: &IpcSender<HostControlMessage>, seq: u64, install: impl FnOnce() -> bool) {
+		let Ok(mut state) = self.state.lock() else {
+			tracing::error!("Failed to lock the frame sink");
+			return;
+		};
+
+		if seq > 1 && seq - 1 > state.last_acked {
+			if let Err(e) = sender.send(HostControlMessage::FrameAck { seq: seq - 1 }) {
+				tracing::debug!("Failed to ack superseded frames to CEF host: {e}");
+			}
+			state.last_acked = seq - 1;
+		}
+		if seq > state.newest_installed && install() {
+			state.newest_installed = seq;
+		}
+		if seq > state.last_acked {
+			if let Err(e) = sender.send(HostControlMessage::FrameAck { seq }) {
+				tracing::debug!("Failed to ack frame to CEF host: {e}");
+			}
+			state.last_acked = seq;
+		}
+	}
+}