Pipeline operators: && and || (#7448)

# Description

We got some feedback from folks used to other shells that `try/catch`
isn't quite as convenient as things like `||`. This PR adds `&&` as a
synonym for `;` and `||` as equivalent to what `try/catch` would do.

# User-Facing Changes

Adds `&&` and `||` pipeline operators.

# 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-cli/src/completions/completer.rs

@@ -127,7 +127,6 @@ impl NuCompleter {
                 match pipeline_element {
                     PipelineElement::Expression(_, expr)
                     | PipelineElement::Redirection(_, _, expr)
-                    | PipelineElement::And(_, expr)
                     | PipelineElement::Or(_, expr) => {
                         let flattened: Vec<_> = flatten_expression(&working_set, &expr);
                         let span_offset: usize = alias_offset.iter().sum();

crates/nu-cli/src/syntax_highlight.rs

@@ -232,7 +232,6 @@ fn find_matching_block_end_in_block(
             match e {
                 PipelineElement::Expression(_, e)
                 | PipelineElement::Redirection(_, _, e)
-                | PipelineElement::And(_, e)
                 | PipelineElement::Or(_, e) => {
                     if e.span.contains(global_cursor_offset) {
                         if let Some(pos) = find_matching_block_end_in_expr(