[clang] Add some CodeGen tests for CWG 4xx issues (#83715)

This patch covers the following defect reports:
[CWG438](https://cplusplus.github.io/CWG/issues/438.html) "Possible flaw
in wording for multiple accesses to object between sequence points",
[CWG439](https://cplusplus.github.io/CWG/issues/439.html) "Guarantees on
casting pointer back to cv-qualified version of original type",
[CWG441](https://cplusplus.github.io/CWG/issues/441.html) "Ordering of
static reference initialization",
[CWG462](https://cplusplus.github.io/CWG/issues/462.html) "Lifetime of
temporaries bound to comma expressions",
[CWG492](https://cplusplus.github.io/CWG/issues/492.html) "`typeid`
constness inconsistent with example".

[CWG475](https://cplusplus.github.io/CWG/issues/475.html) "When is
`std::uncaught_exception()` true? (take 2)" requires a libc++abi test.
As for [CWG454](https://cplusplus.github.io/CWG/issues/454.html) "When
is a definition of a static data member required?", I don't feel
confident in my understanding of it, so skipping over it.