New Rule Proposal: SA1404 but for ExcludeFromCoverage

[mu88]

I'd appreciate having a warning for cases when [ExcludeFromCoverage] is used without a justification, similar to SA1404.

For example, the following code would be a rule violation...

[ExcludeFromCoverage]
public bool Enable()
{
}

...and adding a justification would fix the violation:

[ExcludeFromCoverage(Justification = "Cannot be tested because...")]
public bool Enable()
{
}

If you consider this useful, I'd happily provide a PR.