cbs: Add a table of all supported codec IDs

Use it as the set of codec IDs supported by the trace_headers BSF.

libavcodec/cbs.h

@@ -201,6 +201,14 @@ typedef struct CodedBitstreamContext {
 } CodedBitstreamContext;
 
 
+/**
+ * Table of all supported codec IDs.
+ *
+ * Terminated by AV_CODEC_ID_NONE.
+ */
+extern const enum AVCodecID ff_cbs_all_codec_ids[];
+
+
 /**
  * Create and initialise a new context for the given codec.
  */