interpreter: Add hex/octal/binary support to str and int primitives

[cdown]

Add support for parsing and formatting integers in hexadecimal, octal, and binary representations to complement the existing decimal support.

str.to_int() now accepts strings with 0x/0o/0b prefixes and optional leading signs (+/-), enabling direct parsing of hex, octal, and binary literals while maintaining full backward compatibility with decimal strings including those with leading zeros.

int.to_string() gains a new format keyword argument that accepts 'dec', 'hex', 'oct', or 'bin', allowing integers to be formatted with appropriate prefixes (0x, 0o, 0b). The format parameter works correctly with the existing fill parameter and handles negative numbers properly.

Round-trip conversions are fully supported: values formatted with
int.to_string(format: 'hex') can be parsed back with str.to_int().

Fixes: #2047
Fixes: #15201

[dnicolodi]

Suggested change

	s = self.held_object.strip()
	s_unsigned = s.lstrip('+-').lower()
	if s_unsigned.startswith('0x'):
	base = 16
	elif s_unsigned.startswith('0o'):
	base = 8
	elif s_unsigned.startswith('0b'):
	base = 2
	else:
	base = 10
	return int(s, base)
	return int(s, base=0)

[cdown]

This cannot be done unilaterally because of backwards compatibility. Before this, meson treats "010" as being "10" (decimal), and Python 3's int() with no base (or base=10) also treats it as decimal. However, Python 3's int() with base=0 raises ValueError for strings with leading zeros because it disallows leading zeros for decimal numbers when auto-detecting the base. So while we can indeed use base=0 to simplify some cases, we still need an explicit check for the leading-zero case to maintain backward compatibility.