Update signatures of builtins in the documentation

[serhiy-storchaka]

The following PR updates signatures for all functions and classes in the builtins module. They now match the actual signatures or signatures after solving #73536.

• Consistently add the positional-only parameter mark. It is only used in some signatures, but in others it is not clear whether keyword arguments are accepted for all parameters or all parameters are positional-only.
• Changed the names of some positional-only parameters, for example abs(x) -> abs(number, /).
• Replace non-Python signatures that use [...] with Python signatures or multiple signatures. For example, str.center(width[, fillchar]) -> str.center(width, fillchar= ' ', /) and str.count(sub[, start[, end]]) -> str.count(sub, start=0, stop=None, /).

Linked PRs

• gh-137609: Update signatures of builtins in the documentation #137610
• gh-137609: Change names of some positional-only parameters in builtins #137611

[serhiy-storchaka]

And #137611 changes the names of some positional-only parameters to match the documentation if the names in the documentation look better.