fix: rework directive name handling

[Rich-Harris]

Unfortunately #9462 introduced a bug (cc @paoloricciuti and @dummdidumm) — a directive like use:a.b.c-d needs to become get(a).b['c-d'] if a is state (mutatis mutandis if it's a prop).

This was surfaced by TypeScript as soon as I rewrote member_expression_id_to_literal to return an expression instead of a string (mostly because I wanted a.b.c-d to result in a.b['c-d'] rather than a['b']['c-d'], because serialize_get_binding will only accept an Identifier.

I also got rid of the snapshot test. We should use these extremely sparingly — most of the time we don't care that much about the precise nature of the generated code, we only care about whether the generated code is valid. Snapshot tests are annoying because they frequently need to be updated for reasons unrelated to the test itself.

I'm not sure I agree with the decision in #9462 to do this at transform time rather than parse time. For the sake of things like sourcemap generation, it's good to preserve as much information about node start/end as possible, and it means we can apply this logic in a single place. I haven't done that yet though, we should discuss.

Finally, by working through this problem I think I've uncovered a separate bug — animate/transition directives 'lock on' to the directive value at component init time, even though it may change by the time the directive takes effect. It's less broken than it is on main, but it's still broken. Will create a follow-up issue/PR for that once this is merged.

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[paoloricciuti]

Uh I didn't realized that sorry

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[Rich-Harris]

Not at all! None of this stuff is all that obvious, I was just explicitly flagging it so it didn't seem like i was passively-aggressively rewriting code for no reason :)

[dummdidumm]

The reason I was against adding it to the AST is that for example prettier relies on these fields for printing, because they're verbatim, so no need to extract them from the original source