[lldb][api-test] Add API test for SBCommandInterpreter::CommandOverrideCallback (#94518)

`SBCommandInterpreter::CommandOverrideCallback` was not being exposed to
the Python API and has no coverage in the
API test suite, so this commits exposes and adds a test for it. Doing
this involves also adding a typemap for the callback used for this
function so that it matches the functionality of other callback
functions that are exposed to Python.

lldb/test/API/python_api/interpreter/TestCommandOverrideCallback.py

@@ -0,0 +1,31 @@
+from typing_extensions import override
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class CommandOverrideCallback(TestBase):
+    def setUp(self):
+        TestBase.setUp(self)
+        self.line = line_number("main.c", "Hello world.")
+
+    def test_command_override_callback(self):
+        self.build()
+        exe = self.getBuildArtifact("a.out")
+
+        target = self.dbg.CreateTarget(exe)
+        self.assertTrue(target, VALID_TARGET)
+
+        ci = self.dbg.GetCommandInterpreter()
+        self.assertTrue(ci, VALID_COMMAND_INTERPRETER)
+
+        command_arg = ""
+
+        def foo(*command_args):
+            nonlocal command_arg
+            command_arg = command_args[0]
+
+        self.assertTrue(ci.SetCommandOverrideCallback("breakpoint set", foo))
+        self.expect("breakpoint set -n main")
+        self.assertTrue(command_arg == "breakpoint")