Remove std:vector from MediaExtractor::setMediaCas()

The layout and implementation of std::vector may be different depending
on the compile environment. Now MediaExtractor uses plain c pointer to
pass the token while framework side, IMediaExtractor, keeps using
std:vector.

Test: build
Bug: 67908556
Change-Id: I9614426e1d3318ee6ead5f8f78d5d0120d8c605d