Expose severity to display

See https://github.com/EFForg/rayhunter/issues/334

Severity levels low, medium, high are now exposed to the UI in form of
dotted, dashed and solid lines. The line on the UI represents the
highest-so-far severity seen.

Originally this was intended to be represented by Yellow/Orange/Red, but
this would mean yet another divergence for colorblind mode. This is
colorblind-friendly by default (I think...)

As part of this, simplify EventType so that it becomes a flat "level"
enum without nested variants.

There is also a new debug endpoint that allows one to overwrite the
display level directly for testing.

daemon/src/display/mod.rs

@@ -1,3 +1,6 @@
+use rayhunter::analysis::analyzer::EventType;
+use serde::{Deserialize, Serialize};
+
 mod generic_framebuffer;
 
 pub mod headless;
@@ -9,9 +12,15 @@ pub mod tplink_onebit;
 pub mod uz801;
 pub mod wingtech;
 
-#[derive(Clone, Copy, PartialEq)]
+#[derive(Clone, Copy, PartialEq, Serialize, Deserialize)]
 pub enum DisplayState {
+    /// We're recording but no warning has been found yet.
     Recording,
+    /// We're not recording.
     Paused,
-    WarningDetected,
+    /// A non-informational event has been detected.
+    ///
+    /// Note that EventType::Informational is never sent through this. If it is, it's the same as
+    /// Recording
+    WarningDetected { event_type: EventType },
 }