Optimize Resource constructors

[SimonCropp]

• fix the nullability of the inputs in one of the constructors
• avoid the multiple enumerations of the inputs in 2 of the constructors
• avoid 3x HashSet allocations for 2 of the constructors

Question: should the 3 properties be changes to be ISet instead of ICollection?

[josephdecock]

This is looks good, thanks! For now let's keep the types unchanged, as technically switching away from IEnumerable is a breaking change.