[JIT] Add mutability checks in FunctionSchema and create SchemaInfo subclass (#80734)
- Added overloads to is_mutable method in FunctionSchema to tell whether an argument at index is mutable or an argument with name is mutable.
- Created SchemaInfo subclass of FunctionSchema with constructors from FunctionSchema and from const char* signature.
- Tested is_mutable method overloads in new test_schema_info.cpp file.
**Note that this pr is used to set up SchemaInfo. Implementation for SchemaInfo will be addressed in later commits**
Differential Revision: [D37651384](https://our.internmc.facebook.com/intern/diff/D37651384)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/80734
Approved by: https://github.com/davidberard98
