Keep end of ScriptEditor tab history when closing tab

[TheDying0fLight]

When closing a tab while not at the end of the history all entries after the current idx are deleted. This PRs goal is to ensure that the rest of the history is kept.

Note: There currently is an issue with the history when working with script files (see #113619). So I only used files from the internal documentation for testing this

Example

------- history -----
0 :  AABB
1 :  float <--- this is closed
2 :  ClassDB
3 :  bool
curr idx:  1

Closing 1: float

Without PR

------- history -----
0 :  AABB
curr idx:  0

With PR

------- history -----
0 :  AABB
1 :  ClassDB
2 :  bool
curr idx:  0

[HolonProduction]

I will say that from a purely UX perspective I would expect the following behaviour:

------- history -----
0 :  AABB
1 :  float <--- this is closed
2 :  ClassDB
3 :  bool
curr idx:  1

------- history -----
0 :  AABB
1 :  float <--- this is still part of the history and will reopen the editor when navigated to
2 :  ClassDB
3 :  bool
curr idx:  0

But I think that's not possible with the current data structures used?

[TheDying0fLight]

I agree with your suggestion

When I just remove the part which removes them from the history I get this on indexes with closed files

  ERROR: ./scene/gui/tab_container.cpp:793 - Condition "p_child->get_parent() != this" is true. Returning: -1
  ERROR: Cannot deselect tabs, deselection is not enabled.

But I think it would not be difficult to check if the file is open and then reopen it if it isn't? I will look some more into it

[TheDying0fLight]

@HolonProduction I think this implements your suggestion. One issue I currently still see with this is when a file is reopened which does not exist anymore. But before digging myself deeper into it I wanted to know what you think about this approach