moved key_derivation.rs from pbs_datastore to pbs-config/src/key_config.rs

Also moved pbs-datastore/src/crypt_config.rs to pbs-tools/src/crypt_config.rs.
We do not want to depend on pbs-api-types there, so I use [u8;32] instead of
Fingerprint.

pbs-tools/src/lib.rs

@@ -6,6 +6,7 @@ pub mod broadcast_future;
 pub mod cert;
 pub mod cli;
 pub mod compression;
+pub mod crypt_config;
 pub mod format;
 pub mod fd;
 pub mod fs;