HNBAP, RUA and RANAP protocol codecs

This patch introduces protocol codecs for the HNBAP, RUA and RANAP
protocols, which is mandatory for testing IuCS, IuPS or Iuh in
the future.

As Eclipse TITAN ASN.1 only supports the BER codec and the above
protocols all use APER, we need to use an external transcoder from
APER to BER and vice-versa.  This was implemented using a proprietary
ASN.1 compiler / trnaslator which sysmocom is packaging as
libfftranscode, which is made available as binary package
for Debian 9 at https://ftp.osmocom.org/binaries/libfftranscode/

Related: OS#2856, OS#2857, OS#2858
Change-Id: If4a72de9bc54d6e6a7daaca78a4d4aa5684203a5
diff --git a/library/hnbap/HNBAP_Types.ttcn b/library/hnbap/HNBAP_Types.ttcn
new file mode 100644
index 0000000..0742714
--- /dev/null
+++ b/library/hnbap/HNBAP_Types.ttcn
@@ -0,0 +1,7 @@
+module HNBAP_Types {
+
+	import from HNBAP_PDU_Descriptions language "ASN.1:1997" all;
+
+	external function enc_HNBAP_PDU(in HNBAP_PDU pdu) return octetstring;
+	external function dec_HNBAP_PDU(in octetstring stream) return HNBAP_PDU;
+}