Replace TetheringRequestParcel with TetheringRequest

Replace TetheringRequestParcel with TetheringRequest in the service
code. This makes future changes easier since TetheringRequest is a
proper class and not an AIDL object.

Bug: 216524590
Test: atest TetheringTest TetheringManagerTest
Change-Id: I0cdee597d393e53feb9fe9aff4d6c67330c88599
9 files changed