SAI Editor: Improvements to comments involving waypoints

[Gultask]

With https://github.com/azerothcore/Keira3/pull/2347 Waypoint-related events and actions will change to include their entry in the comments. However, the best solution would be to add the comment related to it instead.

if NULL or '' it should use the entry value. Otherwise the comment on the first point.

For example:

On Point 2 of Path 12300 Reached -> On Point 4 of Path 'Test Creature Path' Reached

entry	pointid	position_x	position_y	position_z	point_comment
12300	1	1	2	3	Test Creature Path
12300	2	2	3	4