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-datastore/src/crypt_writer.rs

@@ -3,7 +3,7 @@ use std::io::Write;
 
 use anyhow::Error;
 
-use super::CryptConfig;
+use pbs_tools::crypt_config::CryptConfig;
 
 pub struct CryptWriter<W> {
     writer: W,