[Data Mapper] Improvements in the top navigation bar

[madushajg]

Description:
Currently two breadcrumbs are available in the DM for navigating where the top-most breadcrumb only navigates through transformation functions and the other breadcrumb navigates within the transformation function, ie: go-to-query.

However it seems this separation complicates the UX, hence it is decided to go with a single breadcrumb for both intra and inter navigation. So the new breadcrumb should looks like the below.

Moreover the function navigation should be enabled for regular functions as well.