Typing support

**Is your feature request related to a problem? Please describe.**
I think it would be great if DearPyGui supported typing.

**Describe the solution you'd like**
`core.pyi` stub file is already generated automatically by `mvPythonParser`, so adding `py.typed` as part of the source is enough for the type checkers to treat the library as typed.

While looking at the current `core.pyi` stub file, I noticed two issues:
- currently, the constants are not typed in the stub file
- this means that using names like `mvKey_Down` would still fail once the `py.typed` file is added until the constants get included in the stub file
- arguments that accept sequences are typed so that they specifically require a list not just any sequence (for example a tuple), even though they do seem to support that just fine

**Describe alternatives you've considered**
None.

**Additional context**
N/A