Add __traits(canCall) and __traits(resolve)

[Atila Neves]

On Saturday, 26 July 2025 at 02:27:08 UTC, Steven Schveighoffer 
wrote:
> Just having run into the problem of `__traits(compiles)` 
> swallowing unexpected errors for the umpteenth time, I'm 
> wondering if we can formally get this feature into the language.
>
> [...]

Both make sense to me. I've also lost count of how many times 
I've had to debug why `__traits(compiles)` was failing.