Move struct cbc bring up code to its own file and functions

This way it's clear and we have in one place all the related code that
neds to be run at a given time.t

Change-Id: I00fe755340664d4ca4a5cfdcae8d4cd33b2f40a1

include/osmocom/cbc/cbc_data.h

@@ -79,6 +79,8 @@ struct cbc {
 };
 
 extern struct cbc *g_cbc;
+struct cbc *cbc_alloc(void *ctx);
+int cbc_start(struct cbc *cbc);
 
 /* rest_api.c */
 int rest_api_init(void *ctx, const char *bind_addr, uint16_t port);

include/osmocom/cbc/debug.h

@@ -1,6 +1,7 @@
 #pragma once
 
 enum {
+	DMAIN,
 	DCBSP,
 	DSBcAP,
 	DREST,