Add an "Adaptive" line wrapping mode for TextEdit

[gelvinp]

Describe the project you are working on

I am prototyping a notion-like text editor.

Describe the problem or limitation you are having in your project

I have an issue with the "Boundary" line wrapping mode. While it works for most reasonable lines with spaces in them, any lines that don't have spaces in them are simply cut off. See below:

boundary.mp4

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

Add a new "Adaptive" case to the LineWrappingMode enum, and an if statement to the set_line_wrapping_mode function that checks for this adaptive case, and if found, uses the TextServer::BREAK_ADAPTIVE break flag on the contained TextParagraph. See below:

adaptive.mp4

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

I have implemented it in this commit:
gelvinp/godot@e1ef595

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

You can't access the TextParagraph to change the break flags from within GDScript.

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

The functionality to do this wrapping is already included in TextServer and used for RichTextLabel, it is just exposing that option to TextEdit.

[Calinou]

cc @bruvzg

[gelvinp]

Forgot to propagate break flags to newly created lines within TextEdit, so I added a commit to fix that.

Here's a link to compare the combined change against master:
https://github.com/gelvinp/godot/compare/master...gelvinp:godot:linewrapping-character?expand=1

[bruvzg]

It's probably should use the same wrap modes as other controls - godotengine/godot#74813 (need more scrollbar / auto-scroll fixes).

[gelvinp]

👍 That probably works better, yeah