stdlib 0.40: reuse dict.update

[inoas]

trafficstars

1. Target branch should be inoas:create-upsert - this branch is rebased to that.
2. Do not merge into next release, but the one after

Followup to https://github.com/gleam-lang/stdlib/issues/570 ~~Potentially closes https://github.com/gleam-lang/stdlib/issues/599~~

[mooreryan]

Closes #599

This doesn't address #599 as far as I can tell. That issue is about a different function that "changes" dictionaries (update, insert, delete), with an as yet to be determined name

[inoas]

Hello! What's this? It seems to be a different function to the one from the issue.

Would you want exactly the behaviour and signature described here? https://github.com/gleam-lang/stdlib/issues/599#issue-2309469182 @lpil

[lpil]

Yes please

[inoas]

Done @lpil https://github.com/gleam-lang/stdlib/pull/659

[inoas]

After doing the other PR I am not certain about the naming https://github.com/gleam-lang/stdlib/pull/659#issuecomment-2220843804