Reimplement `__builtin_dump_struct` in Sema.

Compared to the old implementation:

* In C++, we only recurse into aggregate classes.
* Unnamed bit-fields are not printed.
* Constant evaluation is supported.
* Proper conversion is done when passing arguments through `...`.
* Additional arguments are supported and are injected prior to the
  format string; this directly supports use with `fprintf`, for example.
* An arbitrary callable can be passed rather than only a function
  pointer. In particular, in C++, a function template or overload set is
  acceptable.
* All text generated by Clang is printed via `%s` rather than directly;
  this avoids issues where Clang's pretty-printing output might itself
  contain a `%` character.
* Fields of types that we don't know how to print are printed with a
  `"*%p"` format and passed by address to the print function.
* No return value is produced.

Reviewed By: aaron.ballman, erichkeane, yihanaa

Differential Revision: https://reviews.llvm.org/D124221