Fix clang build with GCC 7.5 (#22415)
cherry-pick of ddf06be97fbf9e8b2b6894f1de87de92f67c452d
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GCC 7.5 rejects two newer C++ idioms:
- LifetimeSafety/FactsGenerator: replace ArrayRef CTAD with an explicit
ArrayRef<const Expr *> to avoid GCC 7's broken brace-init deduction.
- ScalableStaticAnalysisFramework: add explicit std::move() on
unique_ptr<Derived> returns (pre-P1825, GCC 7 won't implicitly move).
No behavior change; restores compatibility with GCC 7.5.
