gh-98836: Extend PyUnicode_FromFormat()

[serhiy-storchaka]

• Support for conversion specifiers o (octal) and X (uppercase hexadecimal).
• Support for length modifiers j (intmax_t) and t (ptrdiff_t).
• Length modifiers are now applied to all integer conversions.
• Support for wchar_t C strings (%ls and %lV).
• Support for variable width and precision (*).
• Support for flag - (left alignment).

• Issue: gh-98836

[vstinner]

Feel free to ignore my suggestions, the PR LGTM.