Use imported names in Command::run signatures (#7967)

# Description

_(Thank you for improving Nushell. Please, check our [contributing
guide](../CONTRIBUTING.md) and talk to the core team before making major
changes.)_

I opened this PR to unify the run command method. It's mainly to improve
consistency across the tree.

# User-Facing Changes

None.

# 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 -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

# 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.

crates/nu-command/src/env/export_env.rs

@@ -2,7 +2,7 @@ use nu_engine::{eval_block, redirect_env, CallExt};
 use nu_protocol::{
     ast::Call,
     engine::{Closure, Command, EngineState, Stack},
-    Category, Example, PipelineData, Signature, Span, SyntaxShape, Type, Value,
+    Category, Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Type, Value,
 };
 
 #[derive(Clone)]
@@ -34,7 +34,7 @@ impl Command for ExportEnv {
         caller_stack: &mut Stack,
         call: &Call,
         input: PipelineData,
-    ) -> Result<nu_protocol::PipelineData, nu_protocol::ShellError> {
+    ) -> Result<PipelineData, ShellError> {
         let capture_block: Closure = call.req(engine_state, caller_stack, 0)?;
         let block = engine_state.get_block(capture_block.block_id);
         let mut callee_stack = caller_stack.captures_to_stack(&capture_block.captures);