Remove dataframes crate and feature

[IanManske]

Description

Removes the old nu-cmd-dataframe crate in favor of the polars plugin. As such, this PR also removes the dataframe feature, related CI, and full releases of nushell.

[fdncred]

Great work on this PR. My main concern is that it will break winget, not due to the rust changes but due to the ci and script changes. That's what all my comments are about.

I started making comments but instead of going through the changes, unrelated to rust code and specific to winget, we need to have the rust flags in order for winget to work. I couldn't remember which flags need to be maintained so I went to lookup the issues which have them and describe why they're needed. Please restore these if/where they're missing.

#9513
#9322 (comment)

[IanManske]

Oh ok, I see the issue with the RUSTFLAGS. However, setting with: rustflags: "" in CI means that the RUSTFLAGS="-D warnings" set by the setup-rust-toolchain action is overwritten. I believe this means that warnings will be ignored (e.g., unused imports like here). For building releases I think it makes sense to restore the old flags.

[fdncred]

Oh ok, I see the issue with the RUSTFLAGS. However, setting with: rustflags: "" in CI means that the RUSTFLAGS="-D warnings" set by the setup-rust-toolchain action is overwritten. I believe this means that warnings will be ignored (e.g., unused imports like here). For building releases I think it makes sense to restore the old flags.

Hopefully winget will pass with these changes. Otherwise, I'll be pinging you to reverse the ci changes.

[IanManske]

Actually what I have right now won't work because of #12900. I'll restore the old flag code for the release workflows @fdncred.

[fdncred]

I think you're one the right track with removing full, I was just worried about the rust flags parts.

[IanManske]

I was just worried about the rust flags parts.

With good reason XD

The target_rustflags and flags were for feature flags (e.g., --features=dataframes), so I kept those removed. ($env.TARGET_RUSTFLAGS is not used/recognized by cargo.)

I also kept the rustflags/RUSTFLAGS as removed in the CI for the reason mentioned before.

Otherwise, feel free to double check that the release workflows have the same rustflags/RUSTFLAGS as before.

[fdncred]

It's pretty clear that all the workflows are different. Only time will tell as to whether winget-pkgs will accept our next release.

[sholderbach]

What I can see by looking at the workflows etc. looks all plausible to me

[sholderbach]

Good catch!

[fdncred]

if we're going to land this, we should do it soon enough to be able to use it a bit before the release.