Add basic functionality of MR2Manager in MR2

As a first step of adding MR2Manager functionality in MR2,
this CL makes MR2 able to:
 - get routes for specific package
 - make transfer / stop

For now, the future system APIs are not marked as @SystemApi yet.
They will be opened with adding CTS tests,
once the implementation is complete.

Bug: 181122201
Test: Manually tested transfer/stop using Support7Demos.
      Test code will be added when MR2Manager's callback functionality
      is implemented.
Change-Id: I71bea98b0ff3e42d193cf04c1b1735fe50c7d673