[LyX/master] Use C++11 string literals to make code easier to read.

[Richard Kimberly Heck]

On 2/26/24 09:24, Thibaut Cuvelier wrote:
> commit 6b1441036f35767c0b60af510222ba792b17b829
> Author: Thibaut Cuvelier <tcuvelier at lyx.org>
> Date:   Mon Feb 26 15:24:36 2024 +0100
>
>      Use C++11 string literals to make code easier to read.

I didn't know about those. I'd guess there are lots of places we could 
make this kind of minor change.

Riki