Mapper.build() currently takes a ContentPath object that it can use to generate
field type names that will include its parent names. We would like to expand field types
to include more information about their parents, and ContentPath does not hold this
information. This commit replaces the ContentPath parameter with a new
MapperBuilderContext, which currently holds only the content path information but
can be expanded in future to hold parent relationship information.
Relates to #75474
9312eba5ed