Properly override Equals and GetHashCode methods for IToken and add tests - #1362

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Nullability of reference types in type of parameter 'obj' of 'bool NameToken.Equals(IToken obj)' doesn't match implicitly implemented member 'bool IEquatable<IToken>.Equals(IToken? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'obj' of 'bool StreamToken.Equals(IToken obj)' doesn't match implicitly implemented member 'bool IEquatable<IToken>.Equals(IToken? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'other' of 'bool DictionaryToken.Equals(DictionaryToken other)' doesn't match implicitly implemented member 'bool IEquatable<DictionaryToken>.Equals(DictionaryToken? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'obj' of 'bool DictionaryToken.Equals(IToken obj)' doesn't match implicitly implemented member 'bool IEquatable<IToken>.Equals(IToken? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'obj' of 'bool CommentToken.Equals(IToken obj)' doesn't match implicitly implemented member 'bool IEquatable<IToken>.Equals(IToken? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'obj' of 'bool InlineImageDataToken.Equals(IToken obj)' doesn't match implicitly implemented member 'bool IEquatable<IToken>.Equals(IToken? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'obj' of 'bool BooleanToken.Equals(IToken obj)' doesn't match implicitly implemented member 'bool IEquatable<IToken>.Equals(IToken? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'obj' of 'bool IndirectReferenceToken.Equals(IToken obj)' doesn't match implicitly implemented member 'bool IEquatable<IToken>.Equals(IToken? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'obj' of 'bool ArrayToken.Equals(IToken obj)' doesn't match implicitly implemented member 'bool IEquatable<IToken>.Equals(IToken? other)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'obj' of 'bool HexToken.Equals(IToken obj)' doesn't match implicitly implemented member 'bool IEquatable<IToken>.Equals(IToken? other)' (possibly because of nullability attributes).