use «chevrons» to represent string literal

[Paul Backus]

On Thursday, 16 January 2025 at 21:19:34 UTC, barbosso wrote:
> They are in the ASCII table.
> They are directional and balanced.
> The D language should use them.
>
> Just look:
> ```
> writeln(«Hello, World!»);
> ```

The obvious follow-on question is, if we allow chevrons, should 
we also allow strings to be enclosed in:

* “Non-ASCII double quotes”?
* 「Chinese corner brackets」?
* 《Tibetan angle brackets》?

If not, why not?