Add toString for TypeSafeMap implementations

mirai-core-utils/src/commonMain/kotlin/TypeSafeMap.kt

@@ -73,6 +73,10 @@ internal open class TypeSafeMapImpl(
         return map.hashCode()
     }
 
+    override fun toString(): String {
+        return "TypeSafeMapImpl(map=$map)"
+    }
+
     override operator fun <T> get(key: TypeKey<T>): T =
         map[key.name]?.uncheckedCast() ?: throw NoSuchElementException(key.toString())
 
@@ -94,6 +98,10 @@ internal class MutableTypeSafeMapImpl(
         return map.hashCode()
     }
 
+    override fun toString(): String {
+        return "MutableTypeSafeMapImpl(map=$map)"
+    }
+
     override operator fun <T> set(key: TypeKey<T>, value: T) {
         map[key.name] = value
     }