[simple] Format freed memory in human-readable format

Shows nicer messages like
memory_freed: 95.95KB, original_size: 191.91KB
memory_freed: 16.03MB, original_size: 40.03MB

instead of

memory_freed: 12594336, original_size: 37760112

Author: Techcable

libs/context/src/utils.rs

@@ -114,7 +114,7 @@ impl Display for MemorySize {
             } else {
                 (1, "")
             };
-            write!(f, "{:.4}{}", bytes as f64 / amount as f64, suffix)
+            write!(f, "{:.2}{}", bytes as f64 / amount as f64, suffix)
         }
     }
 }

libs/simple/src/lib.rs

@@ -579,8 +579,8 @@ impl RawSimpleCollector {
             self.logger, "Finished simple GC";
             "current_thread" => FnValue(|_| ThreadId::current()),
             "num_roots" => num_roots,
-            "original_size" => original_size,
-            "memory_freed" => original_size - updated_size
+            "original_size" => %MemorySize { bytes: original_size },
+            "memory_freed" => %MemorySize { bytes: original_size - updated_size },
         );
     }
 }