bug#61726: [PATCH] Eglot: Support positionEncoding capability

[Eli Zaretskii]

> From: Augusto Stoffel <arstoffel@gmail.com>
> Cc: joaotavora@gmail.com,  61726@debbugs.gnu.org
> Date: Fri, 24 Feb 2023 19:08:14 +0100
> 
> I also didn't attempt to make 'eglot-move-to-bytewise-column' and
> 'eglot-bytewise-column' "correct" in the cases where 'json-serialize'
> throws an error.  I think it's clear that Eli and I have different
> definitions "correctness" in this context, but Eli's proposal requires
> substantial further work, including recovering from possible errors
> raising from 'json-serialize'.

No, it doesn't.  All I'm asking for is to use encode-coding-string or
encode-coding-region to measure the actual number of bytes in a UTF-8
sequence that corresponds to a region of text.  Nothing else is
required or requested.

Can you please humor me and implement eglot-bytewise-column like that?