[clang] Reapply "[Clang][CWG1815] Support lifetime extension of temporary created by aggregate initialization using a default member initializer" (PR #92527)

[via cfe-commits]

bgra8 wrote:

Here's the reproducer:

```c++
struct a {
  virtual int *b();
};
template <class c> struct d : a {
  int *b() { new c; }
};
int *e(a *);
struct f {
  char *g;
};
struct h {};
struct i {
  i(const f &);
  i(h);
};
struct l {
  i j = i({.g = ""});
};
int *k = e(new d<l>);
struct n : l {};
int *m = e(new d<n>);
```

Compilation command:
```
$ clang -c repro.cc
```

This compiles fine with  `clang-18`, trunk `gcc` and previous `clang` revision.

@yronglin can you please have a look?

https://github.com/llvm/llvm-project/pull/92527