(WIP) Start moving from Spans to SpanIDs (attempt no.2)

[kubouch]

Description

Another attempt of converting Spans to SpanIds. First attempt: https://github.com/nushell/nushell/pull/12239

User-Facing Changes

Tests + Formatting

After Submitting

[devyn]

What's the difference between this and the other one?

(…and did you just want to snag #12345? :laughing:)

[kubouch]

The parser/AST side is the same, but in this one, I'm going smarter about it and added an ID field to Span, then later I'll remove its start/end fields and Span will become SpanId. That way I don't need to modify 9999 function signatures that take Span as argument, which turned out to be a major snag in the previous PR.

12345 is just a happy accident :-D

[kubouch]

Let's do it in stages. See https://github.com/nushell/nushell/issues/12963