[clang-tools-extra] [clang] [llvm] Add clang-tidy check to suggest replacement of conditional statement with std::min/std::max (PR #77816)

[Julian Schmidt via cfe-commits]

5chmidti wrote:

> It currently handles this case:
> 
> ```
> if (value1 < value2)
>   value = value2;
> else
>   value = value1;
> ```

When I add 
```c++
  if (value1 < value2)
    value3 = value2;
  else
    value3 = value1;
```
(just renamed `value` to `value3`) to the tests, the check does not suggest using `value3 = std::max(value1, value2);`.

The example from @felix642 used two different expressions on the LHS of the assignment (`value1 = ` and `value2 = `) and correctly does not emit a diagnostic:
```c++
if(value1 < value2)
    value1 = value2;
else
    value2 = value1;
```

https://github.com/llvm/llvm-project/pull/77816