[clang][ASTImporter][StructuralEquivalence] improve StructuralEquivalence on recordType (#76226)

Types comparison in `StructuralEquivalence` ignores its `DeclContext`
when they are generated by template specialization implicitly and this
will produce incorrect result. Add comparison of `DeclContext` of
ClassTemplateSpecializationDecl to improve result.
fix [issue](https://github.com/llvm/llvm-project/issues/65913

)

Co-authored-by: huqizhi <836744285@qq.com>