Add SaferParcelChecker for go/safer-parcel

This was the check used to migrate platform usages of the old deprecated
APIs in ag/16639043. Putting the check in the tree to benefit from the
warnings, which I intend to eventually transform into errors.

Test: atest --host com.google.android.lint.parcel.SaferParcelCheckerTest
Bug: 195622897
Change-Id: Ib6a38efdf88fb4e1fd71195476b6e41a45d8fc0b