…l#11857)

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# Description
<!--
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Description of your pull request goes here. **Provide examples and/or
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Spreading lists automatically when calling externals was deprecated in
0.89 (nushell#11289), and this PR is to remove it in 0.91.

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->

The new error message looks like this:

```
>  ^echo [1 2]
Error: nu::shell::cannot_pass_list_to_external

  × Lists are not automatically spread when calling external commands
   ╭─[entry nushell#13:1:8]
 1 │  ^echo [1 2]
   ·        ──┬──
   ·          ╰── Spread operator (...) is necessary to spread lists
   ╰────
  help: Either convert the list to a string or use the spread operator, like so: ...[1 2]
```

The old error message didn't say exactly where to put the `...` and
seemed to confuse a lot of people, so hopefully this helps.

# Tests + Formatting
<!--
Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used` to
check that you're using the standard code style
- `cargo test --workspace` to check that all tests pass (on Windows make
sure to [enable developer
mode](https://learn.microsoft.com/en-us/windows/apps/get-started/developer-mode-features-and-debugging))
- `cargo run -- -c "use std testing; testing run-tests --path
crates/nu-std"` to run the tests for the standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->

There was one test to check that implicit spread was deprecated before,
updated that to check that it's disallowed now.

# After Submitting
<!-- If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
-->

…l#11857)

<!--
if this PR closes one or more issues, you can automatically link the PR
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e.g.
- this PR should close #xxxx
- fixes #xxxx

you can also mention related issues, PRs or discussions!
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# Description
<!--
Thank you for improving Nushell. Please, check our [contributing
guide](../CONTRIBUTING.md) and talk to the core team before making major
changes.

Description of your pull request goes here. **Provide examples and/or
screenshots** if your changes affect the user experience.
-->

Spreading lists automatically when calling externals was deprecated in
0.89 (nushell#11289), and this PR is to remove it in 0.91.

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->

The new error message looks like this:

```
>  ^echo [1 2]
Error: nu::shell::cannot_pass_list_to_external

  × Lists are not automatically spread when calling external commands
   ╭─[entry nushell#13:1:8]
 1 │  ^echo [1 2]
   ·        ──┬──
   ·          ╰── Spread operator (...) is necessary to spread lists
   ╰────
  help: Either convert the list to a string or use the spread operator, like so: ...[1 2]
```

The old error message didn't say exactly where to put the `...` and
seemed to confuse a lot of people, so hopefully this helps.

# Tests + Formatting
<!--
Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used` to
check that you're using the standard code style
- `cargo test --workspace` to check that all tests pass (on Windows make
sure to [enable developer
mode](https://learn.microsoft.com/en-us/windows/apps/get-started/developer-mode-features-and-debugging))
- `cargo run -- -c "use std testing; testing run-tests --path
crates/nu-std"` to run the tests for the standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->

There was one test to check that implicit spread was deprecated before,
updated that to check that it's disallowed now.

# After Submitting
<!-- If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.
-->