Disable alias recursion (#8397)

# Description

Prevents alias from aliasing itself. It allows a commonly requested
pattern similar to `alias ls = ls -l`.

One small issue is that the syntax highlighting is a bit off:

![alias_itself_no_color](https://user-images.githubusercontent.com/25571562/224545129-8a3ff535-347b-4a4e-b686-11493bb2a33b.png)

Fixes https://github.com/nushell/nushell/issues/8246

# User-Facing Changes

Shouldn't be a breaking change.

# 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-parser/src/parse_keywords.rs

@@ -804,6 +804,13 @@ pub fn parse_alias(
 
             let replacement_spans = &spans[(split_id + 2)..];
 
+            // Temporarily hide the alias itself to prevent recursion
+            let predecl_id = working_set
+                .delta
+                .last_scope_frame_mut()
+                .predecls
+                .remove(&alias_name);
+
             let (expr, err) = parse_call(
                 working_set,
                 replacement_spans,
@@ -812,6 +819,14 @@ pub fn parse_alias(
                 false, // TODO: Should this be set properly???
             );
 
+            if let Some(id) = predecl_id {
+                working_set
+                    .delta
+                    .last_scope_frame_mut()
+                    .predecls
+                    .insert(alias_name.to_vec(), id);
+            }
+
             if let Some(e) = err {
                 if let ParseError::MissingPositional(..) = e {
                     // ignore missing required positional