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/relocate.rs

@@ -199,7 +199,7 @@ pub fn relocate_expr(expr: &mut Expr, location: TextRange) {
                 relocate_expr(expr, location);
             }
         }
-        Expr::LineMagic(nodes::ExprLineMagic { range, .. }) => {
+        Expr::IpyEscapeCommand(nodes::ExprIpyEscapeCommand { range, .. }) => {
             *range = location;
         }
     }