[CIR][CIRGen] Add missing CIRGen for generic bit operation builtins

[Lancern]

This patch adds the CIRGen for the following builtin functions:

• __builtin_clzg;
• __builtin_ctzg;
• __builtin_popcountg.

CIRGen for these three functions are missing in the original PR which introduces CIR bit ops.