Unify round corner radius in PipSurfaceTransactionHelper(s)

Per discussion, will keep the two classes in Launcher and WMShell as for
now and re-address the unification in next release. In this change
- deprecate config_pipEnableRoundCorner since it's now behind a system
  property and waiting to be turned on
- pass the corner radius value from WMShell to Launcher

Video: http://recall/-/aaaaaabFQoRHlzixHdtY/dmUy8qBEMxHShFcFKB3cT3
Bug: 171721389
Test: make sure autoEnterPip has round corner support, see video
Change-Id: If978ee6c3b0307a7423fe51b996f535d7009e74c