gh-113318: Better implementation of @getter and @setter in Argument Clinic

[serhiy-storchaka]

Follow-up to GH-155778.

• The value of a @setter is now a parameter, so it can use a converter, and a @getter can define a return converter. It is optional to declare the value: value: object is added implicitly, with the default NULL if @deleter is applied.
• The accessors of an attribute are now collected in a Property, indexed by the Python name, so the entry of PyGetSetDef is identified by the Python name instead of the C basename. The accessors can therefore use different C basenames, and several implementations of the same accessor can be defined in different preprocessor conditional blocks.
• The entry is composed when all blocks of the file are rendered, instead of by the preprocessor. Half-macros are only generated for an accessor which is compiled conditionally, which removes about 1000 lines from the generated files.

Some setters and getters of _ssl, _asyncio, _ctypes, _sqlite3 and function.__type_params__ now use converters. The error for a wrong type of the value names the attribute instead of an argument of a function:

TypeError: attribute 'verify_mode' must be int, not str

• Issue: Argument Clinic: Better internal implementation for @getter and @setter #113318

[encukou]

Thanks.

I won't have time this week for a line-by-line review, but at first glance this looks good.