"Render whitespace" doesn't show NBSP

Does this issue occur when all extensions are disabled?: Yes

- VS Code Version: VSCodium 1.126.04524
- OS Version: Debian 12 (bookworm)

Steps to Reproduce:

1. Set "Editor: Render Whitespace" (`editor.renderWhitespace`) to "all"
2. View a document that contains a non-breaking space (NBSP)

The NBSP should be rendered, similar to other whitespace, however it is blank.

It seems like VSCode only renders spaces and tabs.

This behaviour can also be reproduced with "Render Whitespace" set to "selection", "boundary", and "trailing".

Other exotic whitespace characters are also not rendered, including figure space (used between digits) and ideographic space (used in CJK).

For comparison, [Meld](https://meldmerge.org/) shows all of them if you enable "Show whitespace".