Update tink-cc dependency to v2

[SanjayVas]

Tink has been restructured into multiple language-specific repositories, so tink-cc is now at https://github.com/tink-crypto/tink-cc with a different directory structure. As a result, any Bazel project depending on private-membership is blocked from updating to tink-cc v2+.

This likely means updating the shell-encryption dependency past google/shell-encryption@779bcfa