String and coments folding scope fix and restructuring

[DinDotDout]

This references issue #84820.
As no discussion was started in the reference issue i tried to fix it according to what seemed to be the expected outcome.
As of now, comments and strings are being folded based on the latest higher indentation level without taking comment/string fold blocks as units. My solution makes it so that they get treated as a block based on the indentation of the starting indent level of the block, which is how comment folding was already being treated and did not translate when they being recursively folded when folding a scope.

As I was finding it difficult to follow what was being done, I restructured fold_line and separated the functionality. If it is not desired it can be reverted easily while keeping the new added functionality.

• Bugsquad edit, fixes: GDScript Editor Nesting bug #84820

[kitbdev]

I think the separation should be reverted, there doesn't need to be multiple methods for this.
Also make sure that the if statements have braces and comments use // and have periods (see here).

related / possibly fixes

• Collapsing a func that ends in a region shows #endregion #90825
• Folds don't work with non-indented content #15690