Background persistence (#505)

* persistence step 1

* fix build

* messages in the background work, notifications not yet

* app state store

* DM icon shows up

* notification launches when app is closed!

* keep ui updated

* lifecycle fixes

* extensive logging, maybe revert later

* send nickname in announcement

* quit in notification

* setting in about sheet

* fix quit bitchat

* lifecycle fixes

* power mode based on background state

* stats for both direciotns

* fix graph persistence

* better counting

* count per device

* only compute when debug sheet is open? untested

* fix read receipts

* fix read receipts fully

* fix unread badge if messages have been read in focus

* foreground promotion fix

* fix app kill in notification

* adjust to new tor

* nice

* about sheet design

app/src/main/java/com/bitchat/android/services/NicknameProvider.kt

@@ -0,0 +1,21 @@
+package com.bitchat.android.services
+
+import android.content.Context
+import com.bitchat.android.ui.DataManager
+
+/**
+ * Provides current user's nickname for announcements and leave messages.
+ * If no nickname saved, falls back to the provided peerID.
+ */
+object NicknameProvider {
+    fun getNickname(context: Context, myPeerID: String): String {
+        return try {
+            val dm = DataManager(context.applicationContext)
+            val nick = dm.loadNickname()
+            if (nick.isNullOrBlank()) myPeerID else nick
+        } catch (_: Exception) {
+            myPeerID
+        }
+    }
+}
+