doxygen: unify use of \file across the board

Considering the various styles and implications found in the sources, edit
scores of files to follow the same API doc guidelines around the doxygen
grouping and the \file tag.

Many files now show a short description in the generated API doc that was so
far only available as C comment.

The guidelines and reasoning behind it is documented at
https://osmocom.org/projects/cellular-infrastructure/wiki/Guidelines_for_API_documentation

In some instances, remove file comments and add to the corresponding group
instead, to be shared among several files (e.g. bitvec).

Change-Id: Ifa70e77e90462b5eb2b0457c70fd25275910c72b
diff --git a/include/osmocom/vty/ports.h b/include/osmocom/vty/ports.h
index a6043b3..8f8ef75 100644
--- a/include/osmocom/vty/ports.h
+++ b/include/osmocom/vty/ports.h
@@ -1,6 +1,4 @@
-#pragma once
-
-/*
+/*! \file ports.h
  * TCP port numbers used for VTY interfaces in osmocom projects. See also the
  * osmocom wiki as well as the osmo-gsm-manuals, which should all be kept in
  * sync with this file:
@@ -8,6 +6,8 @@
  * https://git.osmocom.org/osmo-gsm-manuals/tree/common/chapters/port_numbers.adoc
  */
 
+#pragma once
+
 /* 4238 used by osmo-bts control interface */
 #define OSMO_VTY_PORT_STP	4239
 #define OSMO_VTY_PORT_PCU	4240	/* also: osmo_pcap_client */