Make Parcel::readOutVectorSizeWithCheck public

There are still a few cases of manually defined binder interfaces and
they need to check the size of the vectors against something. That
something is defined here with kMaxAllocationSize.

Test: libsensorserviceaidl_fuzzer
Bug: None
Change-Id: Ie33c74609f9a12212c2e02c81f76477d607a17c0