Validate static asserts

[Andrey Zherikov]

On Friday, 9 September 2022 at 15:22:30 UTC, Ali Çehreli wrote:
> I added and removed '&& false' to every 'static assert' 
> condition manually one by one. :/

It's not CI-friendly :(

> Perhaps a new compiler switch can compile every 'static assert' 
> with an automatic 'false' and dump all their text to the output.

What's about new `compileOutput` trait that returns compiler 
output?
```d
static assert(__traits(compileOutput, { <my code> }) == 
"message");
```