Add OMEMO identity materials long term storage

src/omemo/store.h

@@ -1,5 +1,11 @@
 #include <signal/signal_protocol.h>
 
+#define OMEMO_STORE_GROUP_IDENTITY "identity"
+#define OMEMO_STORE_KEY_DEVICE_ID "device_id"
+#define OMEMO_STORE_KEY_REGISTRATION_ID "registration_id"
+#define OMEMO_STORE_KEY_IDENTITY_KEY_PUBLIC "identity_key_public"
+#define OMEMO_STORE_KEY_IDENTITY_KEY_PRIVATE "identity_key_private"
+
 typedef struct {
    signal_buffer *public;
    signal_buffer *private;