[X86][CodeGen] Support flags copy lowering for CCMP/CTEST (#91849)

```
%1:gr64 = COPY $eflags
OP1 may update eflags
$eflags = COPY %1
OP2 may use eflags
```

To use eflags as input at 4th instruction, we need to use SETcc to
preserve the eflags before 2, and update the source condition of OP2
according to value in GPR %1.

In this patch, we support CCMP/CTEST as OP2.