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_notebook/resources/test/fixtures/jupyter/cell/cell_magic.json

@@ -4,5 +4,10 @@
   "id": "1",
   "metadata": {},
   "outputs": [],
-  "source": ["%%timeit\n", "print('hello world')"]
+  "source": [
+    "%%script bash\n",
+    "for i in 1 2 3; do\n",
+    "  echo $i\n",
+    "done"
+  ]
 }

crates/ruff_notebook/resources/test/fixtures/jupyter/cell/valid_cell_magic.json

@@ -0,0 +1,11 @@
+{
+  "execution_count": null,
+  "cell_type": "code",
+  "id": "1",
+  "metadata": {},
+  "outputs": [],
+  "source": [
+    "%%timeit\n",
+    "print('hello world')"
+  ]
+}

crates/ruff_notebook/resources/test/fixtures/jupyter/ipy_escape_command.ipynb

@@ -26,6 +26,18 @@
     "%%timeit\n",
     "import sys"
    ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "36dedfd1-6c03-4894-bea6-6c1687b82b3c",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "%%random\n",
+    "# This cell is ignored\n",
+    "import pathlib"
+   ]
   }
  ],
  "metadata": {

crates/ruff_notebook/resources/test/fixtures/jupyter/ipy_escape_command_expected.ipynb

@@ -22,8 +22,19 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "%%timeit\n",
-    "import sys"
+    "%%timeit"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "4b6d7faa-72b3-4087-8670-fe6d35e41fb6",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "%%random\n",
+    "# This cell is ignored\n",
+    "import pathlib"
    ]
   }
  ],