feat: no-std support

[huitseeker]

Adds support for no-std.

This is a slight modernization of the miette fork by @bitwalker mentioned in #443, found at https://github.com/bitwalker/miette/compare/main...no-std

All the credit for the contribution goes to @bitwalker, I'm just doing janitorial work around the edges.

[cgettys-microsoft]

To be clear, my comments are just my opinion - I'm neither the author nor am I a maintainer of this library, I'm just a person who has submitted a few contributions previously and was curious. Hope the feedback is helpful.