refactor: set AndroidConfiguration Builder visibility as public (#354)

Co-authored-by: chris <[email protected]>

Author: buongarzoni

rollbar-android/src/main/java/com/rollbar/android/AndroidConfiguration.java

@@ -17,7 +17,7 @@ public AnrConfiguration getAnrConfiguration() {
   public static final class Builder {
     private AnrConfiguration anrConfiguration;
 
-    Builder() {
+    public Builder() {
       anrConfiguration = new AnrConfiguration.Builder().build();
     }