Feature Request: Create comparer for strings

[skarllot]

Create comparer for strings:

[StringEquality(StringComparison.OrdinalIgnoreCase)]
public string Name { get; set; }

[diegofrata]

Somehow missed this issue for a while. I think this is generally a good idea! Happy to take a PR for it.

In the meantime this could be accomplished with:

[CustomEquality(typeof(StringComparer), nameof(StringComparer.OrdinalIgnoreCase))] 

[diegofrata]

This is done as part of #55. Should be available on 3.1.0.