Implement IEquatable to Memory and ReadOnlyMemory (dotnet/corefx#36497)

Implement IEquatable to Memory and ReadOnlyMemory (dotnet/corefx#36497)

* Implement IEquatable to Memory and ReadOnlyMemory

* Add equality tests using IEquatable of ReadOnlyMemory and Memory

* Fix and add tests for Memory and ReadOnlyMemory
* Fixed where IEquatable interface tests were using object.Equals(object) instead of T.Equals(T)
* Added IEquatable interface tests for Memory of different types (char, string)

* Fix IEquatable tests for Memory and ReadOnlyMemory
* Fix tests that were missed in the previous commit (IEquatable tests calling object.Equals(object))
* Should use ReadOnlyMemory in ReadOnlyMemory tests

* Update uapaot baseline for dotnet/corefx#36497

Implementing IEquatable to Memory and ReadOnlyMemory (see dotnet/corefx#32905)

* Update uapaot baseline for dotnet/corefx#36497

Implementing IEquatable to Memory and ReadOnlyMemory (see dotnet/corefx#32905)
* Remove baselines added to System.Runtime by mistake
* Add baselines to System.Memory

* Update uapaot baseline for dotnet/corefx#36497
Implementing IEquatable to Memory and ReadOnlyMemory (see dotnet/corefx#32905)
* Add removed baselines to System.Runtime again

Commit migrated from https://github.com/dotnet/corefx/commit/68920bb0764fb13257f710f44dd08e85e4a35c7c