mu: add fields/flags commands

Useful information for devising queries.

Directly generated from the source. Add manpages, too.

mu/mu-cmd.hh

@@ -45,6 +45,26 @@ Result<void> mu_cmd_find(const Mu::Store& store, const MuConfig* opts);
  */
 Result<void> mu_cmd_extract(const MuConfig* opts);
 
+
+/**
+ * execute the 'fields' command
+ *
+ * @param opts configuration options
+ *
+ * @return Ok() or some error
+ */
+Result<void> mu_cmd_fields(const MuConfig* opts);
+
+/**
+ * execute the 'flags' command
+ *
+ * @param opts configuration options
+ *
+ * @return Ok() or some error
+ */
+Result<void> mu_cmd_flags(const MuConfig* opts);
+
+
 /**
  * execute the 'script' command
  *