Adds a `match` method for eager loading

[Ben52]

I've found this class useful in my own projects. By adding the match method you will now get only a single result, not a collection with a single result when eager or lazy loading your relationship when you call expectOne.

[Ben52]

This is not quite done yet. I'll reopen when its fixed.

[IllyaMoskvin]

Thanks for the contribution! (First PR for AIC's data hub 🎉)

We are currently all-hands-on-deck on another project, but we should have a chance to revisit the more architectural aspects of this one in November. We'll look into merging this then!