Fix back button behavior on OnePlus phones.

Couple things happened:
- Core issue: The device always thought the keyboard was open, so it was
always trying to dismiss the keyboard when you pressed back (instead of
actually going back)
- Big fix: Increase the tolerance of our view height differentialt that
detects if the keyboard is open
- Other fix: the getViewInset() method is always missing on Q, so as a
temp fix we fall back to the status bar height. Gets the calculation to
be closer, even if not truly correct.

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java

@@ -979,9 +979,13 @@ public class ConversationActivity extends PassphraseRequiredActivity
   @Override
   public void onBackPressed() {
     Log.d(TAG, "onBackPressed()");
-    if (reactionOverlay.isShowing())  reactionOverlay.hide();
-    else if (container.isInputOpen()) container.hideCurrentInput(composeText);
-    else                              super.onBackPressed();
+    if (reactionOverlay.isShowing()) {
+      reactionOverlay.hide();
+    } else if (container.isInputOpen()) {
+      container.hideCurrentInput(composeText);
+    } else {
+      super.onBackPressed();
+    }
   }
 
   @Override