[clang] Adding optin.taint.TaintedDiv checker (PR #106389)

[Daniel Krupp via cfe-commits]

dkrupp wrote:

> LGTM overall, I added some minor inline remarks.
> 
> Also consider adding a few simple testcases to distinguish the effects of DivideZero and TaintedDiv. It would also be interesting to highlight what happens in situations like
> 
> ```c
> int test(void) {
>   int x = getchar(); // or any other taint source
>   if (!x)
>     return 5 / x;
>   return 8;
> }
> ```
> 
> (I presume that in this case core.DivideZero will create a bug report, but the new TaintedDiv checker won't.)

Test added.

https://github.com/llvm/llvm-project/pull/106389