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.

lib/src/analysis/incomplete_sib.rs

@@ -2,7 +2,7 @@ use std::borrow::Cow;
 
 use telcom_parser::lte_rrc::{BCCH_DL_SCH_MessageType, BCCH_DL_SCH_MessageType_c1};
 
-use super::analyzer::{Analyzer, Event, EventType, Severity};
+use super::analyzer::{Analyzer, Event, EventType};
 use super::information_element::{InformationElement, LteInformationElement};
 
 pub struct IncompleteSibAnalyzer {
@@ -44,9 +44,7 @@ impl Analyzer for IncompleteSibAnalyzer {
             && sib1.scheduling_info_list.0.len() < 2
         {
             return Some(Event {
-                event_type: EventType::QualitativeWarning {
-                    severity: Severity::Medium,
-                },
+                event_type: EventType::Medium,
                 message: format!(
                     "SIB1 scheduling info list was malformed (packet {})",
                     self.packet_num