ctrl: Introduce cmd SET subscriber.create <imsi>

Create a new subscriber from CTRL, similar to VTY command
"imsi IDENT create".

On success SET_REPLY contains the ID of the newly created subscriber.

Related: SYS#5993
Change-Id: Id1b760cd07712245a0eeabaac7891bce93c1fe8e
diff --git a/src/logging.c b/src/logging.c
index eab0510..6f0f3d2 100644
--- a/src/logging.c
+++ b/src/logging.c
@@ -43,6 +43,12 @@
 		.color = "\033[1;35m",
 		.enabled = 1, .loglevel = LOGL_NOTICE,
 	},
+	[DCTRL] = {
+		.name = "DCTRL",
+		.description = "Osmocom CTRL interface",
+		.color = "\033[1;30m",
+		.enabled = 1, .loglevel = LOGL_NOTICE,
+	},
 };
 
 const struct log_info hlr_log_info = {