Skip comparing variableResolver if underlying type is Class

[quaff]

Before this commit, given:

ResolvableType type1 = ResolvableType.forClassWithGenerics(IProvider.class, String.class);
ResolvableType type2 = ResolvableType.forClassWithGenerics(IProvider.class,ResolvableType.forClass(StringProvider.class).as(IProvider.class).getGenerics());
assertThat(type1).isEqualTo(type2);

will cause:

Expected :org.springframework.core.ResolvableTypeTests$IProvider<java.lang.String>
Actual   :org.springframework.core.ResolvableTypeTests$IProvider<java.lang.String>

[snicoll]

Thanks for the PR but you should be using equalsType for that type of comparison. The regular equals implementation is rather strict since it is primarily used for cache lookups, not for type comparisons.