Remove persistent collections Equals/GetHashCode overrides

[bahusoid]

To make behavior consistent with standard collections.
Related to #2457

[fredericDelaporte]

I am not convinced aligning with standard collections on this matter is worth the possible breaking change for application code currently relying on NHibernate Equals overrides for these collections.

As showcased by #2457, these overrides may cause in some cases failures, but it does not seem to be a frequently annoying pitfall, judging by the number of issues I have seen related to this. (#2457 is the first and only I have seen currently.)

(Due to this I am not decided on which type label it should have. Improvement? Task?)

[bahusoid]

I am not convinced aligning with standard collections on this matter is worth the possible breaking change for application code currently relying on NHibernate Equals overrides for these collections.

I'm pretty sure that the fact that Equals call make collection be eager loaded is not noticed by most users but it's not desired behavior for most of them. As it's stated in the issue - they have such problem for long time unnoticed and only fail shows them the issue.

Also this behavior is not consistent with our other persistent collections - for instance there is no override for bags.

Also the fact that behavior is different for persistent and transient entity is also disturbing.

Maybe Equals/GetHashcode methods really need to be overridden but with the following logic:
If it's initialized call Equals/GetHashcode on wrapped collection instead. If it's not - call reference equality.

But as first step - get rid of object equality where it's present I consider as good change anyway.

[fredericDelaporte]

I'm pretty sure that the fact that Equals call makes collection be eager loaded is not noticed by most users but it's not desired behavior for most of them.

Well ok.