Added more package-related files to gitignore

UOP1_Project/.gitignore

 # Crashlytics generated file
 crashlytics-build.properties
 
-# Individual Package settings that can safely be ignored
+# Package related files that can be ignored or are better kept user-specific
+ProjectSettings/Packages/com.unity.polybrush/Settings.json
+Assets/Polybrush Data*
+Assets/PolybrushData*