Stub generator for proxy classes does not generate overload stubs

[vfazio]

Describe the bug

The stub generator for proxy classes (tools/write_pyi.py) does not generate overload stubs

Expected behavior

To accurately reflect the typing of the proxied classes, the overloads should be stubbed out.

[CaselIT]

Hi,

this seems a duplicate of #1146. We can continue to the other one