feat: adds local halfchan fees to listpeers

This will add `fee_base` (msat) and `fee_ppm` (u32 num) to the RPC
`listpeers` output.

Changelog-Added: fee_base and fee_ppm to listpeers

lightningd/peer_control.c

@@ -877,6 +877,12 @@ static void json_add_channel(struct lightningd *ld,
 	json_add_amount_msat_compat(response, funding_msat,
 				    "msatoshi_total", "total_msat");
 
+	/* routing fees */
+	json_add_amount_msat_only(response, "fee_base_msat",
+				  amount_msat(channel->feerate_base));
+	json_add_u32(response, "fee_proportional_millionths",
+		     channel->feerate_ppm);
+
 	/* channel config */
 	json_add_amount_sat_compat(response,
 				   channel->our_config.dust_limit,

lightningd/test/run-invoice-select-inchan.c

@@ -224,6 +224,12 @@ void json_add_amount_msat_compat(struct json_stream *result UNNEEDED,
 				 const char *msatfieldname)
 
 { fprintf(stderr, "json_add_amount_msat_compat called!\n"); abort(); }
+/* Generated stub for json_add_amount_msat_only */
+void json_add_amount_msat_only(struct json_stream *result UNNEEDED,
+			  const char *msatfieldname UNNEEDED,
+			  struct amount_msat msat)
+
+{ fprintf(stderr, "json_add_amount_msat_only called!\n"); abort(); }
 /* Generated stub for json_add_amount_sat_compat */
 void json_add_amount_sat_compat(struct json_stream *result UNNEEDED,
 				struct amount_sat sat UNNEEDED,