[JIT] Modify is_mutable in FunctionSchema and SchemaInfo to have SchemaArgument parameter instead of index (#81784)
- Modify the is_mutable(size_t index) overload to become is_mutable(const SchemaArgument& argument) due to cases where one might want to check the mutability of either input or output arguments.
- Refactored all calls to the function to use this new overload
- Tested through is_mutable() tests in test_schema_info.cpp
Pull Request resolved: https://github.com/pytorch/pytorch/pull/81784
Approved by: https://github.com/davidberard98
