Argument Clinic: c_default does not work with bool and char converters

[serhiy-storchaka]

The c_default option of the bool and char converters does not have effect.

It is especially bad for bool where the default value other than 0 and 1 can be used to detect whether the argument was passed. I have a quick and dirty fix for this.

For char, a serious rewrite of Argument Clinic is needed.

Linked PRs

• gh-132753: Argument Clinic: Fix support of c_default for the bool converter #132754
• [3.13] gh-132753: Argument Clinic: Fix support of c_default for the bool converter (GH-132754) #132766