[CIR][CIRGen][LLVMLowering] Add support for checked arithmetic builtins

[Lancern]

This patch adds support for checked arithmetic builtins, including:

• __builtin_add_overflow and __builtin_{s|u}add{|l|ll}_overflow;
• __builtin_sub_overflow and __builtin_{s|u}sub{|l|ll}_overflow;
• __builtin_mul_overflow and __builtin_{s|u}mul{|l|ll}_overflow.

This patch adds a new operation cir.checked_arith to represent these builtins. Unlike other CIR operations, this new operation has two result values. One for the possibly truncated result, and the other for a boolean flag that indicates whether the operation has overflowed.

CIRGen and LLVMIR lowering support for the new operation is both included in this PR.

[Lancern]

Rebased onto the latest main.

[Lancern]

Rebased onto the latest main.

[Lancern]

Rebased onto the latest main.