Rename Magic* to IpyEscape* (#6395)

## Summary

This PR renames the `MagicCommand` token to `IpyEscapeCommand` token and
`MagicKind` to `IpyEscapeKind` type to better reflect the purpose of the
token and type. Similarly, it renames the AST nodes from `LineMagic` to
`IpyEscapeCommand` prefixed with `Stmt`/`Expr` wherever necessary.

It also makes renames from using `jupyter_magic` to
`ipython_escape_commands` in various function names.

The mode value is still `Mode::Jupyter` because the escape commands are
part of the IPython syntax but the lexing/parsing is done for a Jupyter
notebook.

### Motivation behind the rename:
* IPython codebase defines it as "EscapeCommand" / "Escape Sequences":
* Escape Sequences:
292e3a2345/IPython/core/inputtransformer2.py (L329-L333)
* Escape command:
292e3a2345/IPython/core/inputtransformer2.py (L410-L411)
* The word "magic" is used mainly for the actual magic commands i.e.,
the ones starting with `%`/`%%`
(https://ipython.readthedocs.io/en/stable/interactive/reference.html#magic-command-system).
So, this avoids any confusion between the Magic token (`%`, `%%`) and
the escape command itself.
## Test Plan

* `cargo test` to make sure all renames are done correctly.
* `grep` for `jupyter_escape`/`magic` to make sure all renames are done
correctly.

crates/ruff_python_ast/src/visitor.rs

@@ -312,7 +312,7 @@ pub fn walk_stmt<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, stmt: &'a Stmt) {
         Stmt::Global(_) => {}
         Stmt::Nonlocal(_) => {}
         Stmt::Expr(ast::StmtExpr { value, range: _ }) => visitor.visit_expr(value),
-        Stmt::Pass(_) | Stmt::Break(_) | Stmt::Continue(_) | Stmt::LineMagic(_) => {}
+        Stmt::Pass(_) | Stmt::Break(_) | Stmt::Continue(_) | Stmt::IpyEscapeCommand(_) => {}
     }
 }
 
@@ -543,7 +543,7 @@ pub fn walk_expr<'a, V: Visitor<'a> + ?Sized>(visitor: &mut V, expr: &'a Expr) {
                 visitor.visit_expr(expr);
             }
         }
-        Expr::LineMagic(_) => {}
+        Expr::IpyEscapeCommand(_) => {}
     }
 }