Allow transparent cell magics (#8911)

## Summary

This PR updates the logic for `is_magic_cell` to include certain cell
magics. These cell magics would contain Python code following the line
defining the command. The code could define a variable which can then be
referenced in other cells. Currently, we would ignore the cell
completely leading to undefined-name violation.

As discussed in
https://github.com/astral-sh/ruff/issues/8354#issuecomment-1832221009

## Test Plan

Add new test case to validate this scenario.

crates/ruff_linter/src/snapshots/ruff_linter__linter__tests__ipy_escape_command.snap

@@ -19,5 +19,20 @@ ipy_escape_command.ipynb:cell 1:5:8: F401 [*] `os` imported but unused
 5   |-import os
 6 5 | 
 7 6 | _ = math.pi
+8 7 | %%timeit
+
+ipy_escape_command.ipynb:cell 2:2:8: F401 [*] `sys` imported but unused
+  |
+1 | %%timeit
+2 | import sys
+  |        ^^^ F401
+  |
+  = help: Remove unused import: `sys`
+
+ℹ Safe fix
+6 6 | 
+7 7 | _ = math.pi
+8 8 | %%timeit
+9   |-import sys