coap: deprecate COAP_CT_ content type defines

COAP_CT_ style defines for the content types are deprecated in favour of
COAP_FORMAT_ style defines. COAP_FORMAT_ is expanded to include any
missing content type that was available with COAP_CT_.

sys/include/net/coap.h

@@ -123,6 +123,8 @@ extern "C" {
 
 /**
  * @name    Content types
+ * @deprecated  Deprecated in favour of [COAP_FORMAT_](@ref net_coap_format)
+ *              style defines
  * @{
  */
 #define COAP_CT_LINK_FORMAT     (40)
@@ -134,11 +136,14 @@ extern "C" {
 
 /**
  * @name    Content-Format option codes
+ * @anchor  net_coap_format
  * @{
  */
 #define COAP_FORMAT_TEXT         (0)
 #define COAP_FORMAT_LINK        (40)
+#define COAP_FORMAT_XML         (41)
 #define COAP_FORMAT_OCTET       (42)
+#define COAP_FORMAT_EXI         (47)
 #define COAP_FORMAT_JSON        (50)
 #define COAP_FORMAT_CBOR        (60)
 /** @} */