Style: Partially apply clang-tidy's cppcoreguidelines-pro-type-member-init

Didn't commit all the changes where it wants to initialize a struct
with `{}`. Should be reviewed in a separate PR.

Option `IgnoreArrays` enabled for now to be conservative, can be
disabled to see if it proposes more useful changes.

Also fixed manually a handful of other missing initializations / moved
some from constructors.

editor/debugger/editor_performance_profiler.h

@@ -66,7 +66,7 @@ private:
 	Control *monitor_draw = nullptr;
 	Label *info_message = nullptr;
 	StringName marker_key;
-	int marker_frame;
+	int marker_frame = 0;
 	const int MARGIN = 4;
 	const int POINT_SEPARATION = 5;
 	const int MARKER_MARGIN = 2;