use vector<uint8_t> for byte[] in AIDL

In native world, byte stream is typically represented in uint8_t[]
or vector<uint8_t>. C++ backend already generates that way. This
change involves NDK backend.

Now NDK backend also uses vector<uint8_t> just like C++ backend.

Bug: 144957764
Test: atest CtsNdkBinderTestCases
Change-Id: Iffe188aa42f4f827ad4d021f06d85992db204c0d