Integrate new result macros. (#1780)

* result: try out some experimental shenanigans

* result: sketch out some more shenanigans

* result: see what it looks like to convert kernel to use result conds instead of guards

* make rest of kernel use experimental new macro-ing

libraries/libmesosphere/source/kern_k_page_group.cpp

@@ -81,7 +81,7 @@ namespace ams::kern {
         }
         m_last_block = new_block;
 
-        return ResultSuccess();
+        R_SUCCEED();
     }
 
     void KPageGroup::Open() const {