Notification settings, importance and pre-O apps

- Show pre-O settings for the misc channel, should the app still have it
(versus the full channel settings)
- Fix the importance summmary text in various places
- Update the color of the blocked description text
- Fix what fields appear/disappear based on blocked status and importance

Fixes: 38177887
Bug: 38120923
Fixes: 38012300
Fixes: 37923612
Test: manual, with an O app, a pre O app that has channels, and a pre-O
app with no channels
Change-Id: I42965b81b795e8fb427f857c7766fe5480a99f2e

src/com/android/settings/notification/NotificationBackend.java

@@ -148,6 +148,15 @@ public class NotificationBackend {
         }
     }
 
+    public boolean onlyHasDefaultChannel(String pkg, int uid) {
+        try {
+            return sINM.onlyHasDefaultChannel(pkg, uid);
+        } catch (Exception e) {
+            Log.w(TAG, "Error calling NoMan", e);
+            return false;
+        }
+    }
+
     static class Row {
         public String section;
     }