Add a log viewer to Spinner.

This is more of a proof-of-concept/demo for using a websocket with
Spinner. Gives an example of how we could push live updates to the
webapp.

Also, the logger is actually nice. Guaranteed to never get cluttered
with system logs. Looks basically identical to our other log viewers.
Filtering is basic but fast. And we could build much better tooling on
top of this.

app/src/androidTest/java/org/thoughtcrime/securesms/SignalInstrumentationApplicationContext.kt

@@ -26,9 +26,7 @@ class SignalInstrumentationApplicationContext : ApplicationContext() {
   }
 
   override fun initializeLogging() {
-    persistentLogger = PersistentLogger(this)
-
-    Log.initialize({ true }, AndroidLogger(), persistentLogger, inMemoryLogger)
+    Log.initialize({ true }, AndroidLogger(), PersistentLogger(this), inMemoryLogger)
 
     SignalProtocolLoggerProvider.setProvider(CustomSignalProtocolLogger())