split MintDatabase into separate narrower scoped traits

- MintKeysDatabase
- MintQuotesDatabase
- MintProofsDatabase
- MintSignaturesDatabase

This commit splits the MintDatabase trait with 30+ methods into a series
of smaller traits, each dedicate to a specific subsystem of the mint
service.

crates/cdk-integration-tests/src/init_auth_mint.rs

@@ -19,7 +19,7 @@ pub async fn start_fake_mint_with_auth<D, A>(
     auth_database: A,
 ) -> Result<()>
 where
-    D: MintDatabase<Err = cdk_database::Error> + Send + Sync + 'static,
+    D: MintDatabase<cdk_database::Error> + Send + Sync + 'static,
     A: MintAuthDatabase<Err = cdk_database::Error> + Send + Sync + 'static,
 {
     let fee_reserve = FeeReserve {