Backported from enterprise-firefox 16d9ea9e4e79.
Threads an explicit key_size through keystore_create_dek (LockstoreService,
lockstore_ffi, keystore.rs, nsILockstore.idl); SQLiteEncryption passes
kDekBytes and static_asserts kDekBytes == IPCStreamCipherStrategy::KeyType size.
Also updates the lockstore gtest call sites (TestLockstoreKeystore.cpp,
TestLockstoreDatastore.cpp, TestLockstoreService.cpp) to the new 5-arg arity;
the enterprise commit updated only TestLockstoreService.cpp, leaving the other
two on the old signature (a latent build break).
Differential Revision: https://phabricator.services.mozilla.com/D304993
Benjamin Beurdouche
954b131b65