Port update cells command

[rusty-jules]

Description

Hello! I have done a port of update cells, even though I did not sign up for it. This was really just a learning experience for me to dip my toe into contributing to nushell (I love this tool!!), but only after writing this did I notice that this port had been assigned to @kubouch (I'm assuming) in nushell/nushell#4356, although it had not been assigned in #242 which is what I had been looking at. Did not mean to not follow protocol so I don't mind closing if this is unhelpful.

Tests

• cargo fmt --all -- --check to check standard code formatting (cargo fmt --all applies these changes)
• cargo clippy --all --all-features -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect to check that you're using the standard code style <-- this failed here
• cargo build; cargo test --all --all-features to check that all the tests pass

Notes

I really went into this blind and probably did some things in a non-idiomatic way, but the tests from the original are passing. There are currently two FIXMEs [one, two] where I had questions.

[kubouch]

Haha, that's fine, I haven't started yet! Thanks for the effort!

[rusty-jules]

Whoops, a last minute attempt to make the code prettier broke it. I've reverted it back to a less-pretty if statement. I promise it passes this time! So much for a good first impression 😅

[sophiajt]

@rusty-jules - heh, no worries. For that clippy error, you'll need to update your code following clippy's suggestions. Instead of unwrapping, we have a standard error we use everywhere: ShellError. You can check for the possible error and return ShellError, or, if the error is impossible, use .expect. The other clippy warning I think you can turn your .into_iter() to just .iter()

[kubouch]

@rusty-jules I left a comment. Otherwise looks good to me.

[kubouch]

Looks good thanks a lot!