crypto: Erase key from RAM after storing into enclave

When storing a new unique secret key in the secure enclave, it is
temporarily stored in a stack buffer accessible by CPU1.
Since it is a secret key, it should not be kept in memory as it could
be leaked.

This commit calls the explicit_bzero() function from the libc to ensure
that the buffer containing the key is cleared. Unlike with bzero() and
memset(), the compiler won't optimize away calls to explicit_bzero().

applications/services/crypto/crypto_cli.c

@@ -276,6 +276,7 @@ void crypto_cli_store_key(Cli* cli, FuriString* args) {
         }
     } while(0);
 
+    explicit_bzero(data, sizeof(data));
     furi_string_free(key_type);
 }