Add support for foldable comment blocks

[SeremTitus]

Describe the project you are working on

Code editor should have foldable comments to allow working with lengthy comments

Describe the problem or limitation you are having in your project

none

Describe the feature / enhancement and how it helps to overcome the problem or limitation

Enhance user experience with code editor in godot

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

this pull request explores implementation

• SeremTitus:folding-doc-comments

If this enhancement will not be used often, can it be worked around with a few lines of script?

no, the API to achieve this feature are not exposed

Is there a reason why this should be core and not an add-on in the asset library?

the API to achieve this feature are not exposed

[AThousandShips]

Already possible since 4.2