Add wordWrapColumn and bounded line wrapping modes.

[AlbertHilb]

Currently, in text editors, you can choose to not break line or to break line at viewport border.
I think it would be useful to have also the possibility to break line at a given column or at the minimum between the given column and the viewport width.

This PR adds a new property, wordWrapColumn, to the editorConfigsection of jupyterlab settings and changes lineWrap setting to accept one of the following string values:

• off: lines never wrap,
• on: lines wrap at viewport border,
• wordWrapColumn: lines wrap at column specified by wordWrapColumn parameter,
• bounded: lines wrap at minimum between viewport width and wordWrapColumn parameter.

This is the same setting schema used by VSCode.

Cheers

[blink1073]

Looks great, thanks! I don't have a computer for the next few days to try it locally, so I'll leave this open for now.

[blink1073]

Thanks again!