[Clang] Fix CXXRewrittenBinaryOperator::getDecomposedForm to handle case when...

[Clang] Fix CXXRewrittenBinaryOperator::getDecomposedForm to handle case when spaceship operator returns comparison category by reference (#66270)

Currently CXXRewrittenBinaryOperator::getDecomposedForm(...) may crash
if the spaceship operator returns a comparison category by reference. This
because IgnoreImplicitAsWritten() does not look through CXXConstructExpr. The
fix is to use IgnoreUnlessSpelledInSource() which will look though
CXXConstructExpr.

This fixes: https://github.com/llvm/llvm-project/issues/64162