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/remote.rs

@@ -0,0 +1,34 @@
+use crate::consts::BROWSER_HOST_CONFIG_FLAG;
+
+pub(crate) mod host;
+pub(crate) mod messages;
+pub(crate) mod spawn;
+
+#[derive(serde::Serialize, serde::Deserialize)]
+pub(crate) struct HostConfig {
+	pub(crate) server: String,
+	pub(crate) main_pid: u32,
+	pub(crate) acceleration: bool,
+	#[cfg(target_os = "linux")]
+	pub(crate) frame_socket_fd: Option<std::os::fd::RawFd>,
+	#[cfg(target_os = "macos")]
+	pub(crate) frame_service: Option<String>,
+}
+
+impl HostConfig {
+	pub(crate) fn to_arg(&self) -> String {
+		let json = serde_json::to_string(self).expect("HostConfig always serializes");
+		format!("{BROWSER_HOST_CONFIG_FLAG}{json}")
+	}
+
+	pub(crate) fn from_args(args: &[String]) -> Option<Self> {
+		let json = args.iter().find_map(|arg| arg.strip_prefix(BROWSER_HOST_CONFIG_FLAG))?;
+		match serde_json::from_str(json) {
+			Ok(config) => Some(config),
+			Err(e) => {
+				tracing::error!("Malformed host config on the command line: {e}");
+				None
+			}
+		}
+	}
+}