Introduce string resource for notification content

mailbox/src/main/java/org/briarproject/mailbox/MailboxNotificationManager.kt

@@ -50,8 +50,8 @@ class MailboxNotificationManager @Inject constructor(
                 ctx, 0, notificationIntent, 0
             )
             return NotificationCompat.Builder(ctx, CHANNEL_ID)
-                .setContentTitle(ctx.getString(R.string.notification_mailbox_running))
-                .setContentText("Waiting for messages...")
+                .setContentTitle(ctx.getString(R.string.notification_mailbox_title))
+                .setContentText(ctx.getString(R.string.notification_mailbox_content))
                 .setSmallIcon(R.drawable.ic_launcher_foreground)
                 .setContentIntent(pendingIntent)
                 .setPriority(PRIORITY_MIN)

mailbox/src/main/res/values/strings.xml

 <resources>
     <string name="app_name">Briar Mailbox</string>
     <string name="notification_channel_name">Briar Mailbox Channel</string>
-    <string name="notification_mailbox_running">Briar Mailbox running</string>
+    <string name="notification_mailbox_title">Briar Mailbox running</string>
+    <string name="notification_mailbox_content">Waiting for messages…</string>
 </resources>
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