many: update for lib/message updates

Adapt to the new names / directory. Big commit, but mostly just very boring renaming.

lib/mu-store.hh

@@ -34,7 +34,7 @@
 #include <index/mu-indexer.hh>
 #include <mu-query-results.hh>
 #include <utils/mu-utils.hh>
-#include <mu-message.hh>
+#include <message/mu-message.hh>
 
 namespace Mu {
 
@@ -156,7 +156,7 @@ public:
 	 */
 	std::mutex& lock() const;
 	Option<QueryResults> run_query(const std::string&	expr        = "",
-				       std::optional<Message::Field::Id>    sortfield_id = {},
+				       std::optional<Field::Id>    sortfield_id = {},
 				       QueryFlags		flags       = QueryFlags::None,
 				       size_t			maxnum      = 0) const;
 
@@ -287,7 +287,7 @@ public:
 	 *
 	 * @return the number of times func was invoked
 	 */
-	size_t for_each_term(Message::Field::Id id, ForEachTermFunc func) const;
+	size_t for_each_term(Field::Id id, ForEachTermFunc func) const;
 
 
 	/**