add long-press + notif based mode switching

oooooh boy, this is looking pretty slick. I'm kind-of impressed I was
able to throw this together in ~2 days of post-work hacking (though I
guess they were some pretty late-nights...)

There's really only one feature left that I _need_ to implement, which
is the on-disk persistence for selected mode. That shouldn't be too
tricky though...

src/controller/controls/dpad.rs

@@ -3,7 +3,7 @@ use std::sync::mpsc;
 use std::thread::JoinHandle;
 use std::time::Duration;
 
-use crate::controller::ControlMode;
+use crate::controller::{ControlMode, ControlModeMeta};
 use crate::dial_device::DialHaptics;
 use crate::fake_input::FakeInput;
 use crate::DynResult;
@@ -123,6 +123,13 @@ impl DPad {
 }
 
 impl ControlMode for DPad {
+    fn meta(&self) -> ControlModeMeta {
+        ControlModeMeta {
+            name: "Paddle",
+            icon: "input-gaming",
+        }
+    }
+
     fn on_start(&mut self, haptics: &DialHaptics) -> DynResult<()> {
         haptics.set_mode(false, Some(3600))?;
         Ok(())