Cleanup dagger setup (#2300)

* cleanup dagger setup

* fix tests

* fix ktlint

* cleanup FragmentBuildersModule

app/src/main/java/com/keylesspalace/tusky/appstore/EventsHub.kt

@@ -2,21 +2,19 @@ package com.keylesspalace.tusky.appstore
 
 import io.reactivex.rxjava3.core.Observable
 import io.reactivex.rxjava3.subjects.PublishSubject
+import javax.inject.Inject
+import javax.inject.Singleton
 
 interface Event
 interface Dispatchable : Event
 
-interface EventHub {
-    val events: Observable<Event>
-    fun dispatch(event: Dispatchable)
-}
-
-object EventHubImpl : EventHub {
+@Singleton
+class EventHub @Inject constructor() {
 
     private val eventsSubject = PublishSubject.create<Event>()
-    override val events: Observable<Event> = eventsSubject
+    val events: Observable<Event> = eventsSubject
 
-    override fun dispatch(event: Dispatchable) {
+    fun dispatch(event: Dispatchable) {
         eventsSubject.onNext(event)
     }
 }