Fix missing tooltips caused by export_category

[garychia]

This pull request attempts to fix the issues mentioned by #64432 and #68520.

Problems found:

1. The EditorInspector::update_tree function did not update the doc_name variable when skipping a category, which happened when show_categories was set to false and caused the following properties could not be identified (editor_inspector.cpp, line 2725).
2. In the same function, the name of an export_category was treated as a class name as if it were a script.

Solutions:

1. Find out the name of class a skipped category belongs to and update doc_name with it.
2. Add the corresponding script path to hint_string of an export_category, which allows the function to find out the corresponding class.

Bugsquad edit:

• Fix GDScript 2.0: @export_category interferes with the property inspector tooltip #64432
• Fix @export_category breaks export var tooltips #68520

[Atermnus]

Finally! Having custom resources with a lot of options and no documentation can create extremely verbose typing situations.

[YuriSizov]

I don't like how hacky this whole doc_name things became, the logic is hard to follow. I feel like we should have some metadata for each property instead, which points to which class this property originates from. The way it works now is very much order dependent and, yes, easy to break when users starts to mess with custom categories.

PS. But, for what it's worth, this particular PR doesn't do anything we don't already do, and from the looks of it it should fix the issue (not tested yet).

[garychia]

I agree. I think my solution may not be complete although it solved the issues on my machine. There might be some bugs I did not found. I believe the update_tree function should be refactored in the future. Otherwise, it won't be easy to debug.
By the way, it seems that doc_info_cache is not updated when the doc is changed. But I'm not sure.

[akien-mga]

• Superseded by Fix @export_category interfering with property tooltips #76147.

Thanks for the contribution nonetheless!