Don't use hidden Parcel#{read,write}CharSequence

Make ContactsRequest no longer parcelable in order
to avoid calling hidden APIs.

ContactsRequest only needs to be parcelable for the
sake of ContactsSearchManager. ContactsSearchManager
only exists for the sake of supporting the
FILTER_CONTACTS intent filter. The FILTER_CONTACTS intent
was only used by the system's search button which the contacts
app hasn't supported since gingerbread. Moreover, the FILTER_CONTACTS
API is deprecated.

Therefore, I remove all the things mentioned above.

Bug: 18777272
Change-Id: I8da1ff02bcdebce08acc5eac47d479b8d9617483