optimizer: early `finalize` insertion
Currently, in the finalizer inlining pass, if not all the code between
the finalizer registration and the end of the object’s lifetime (i.e.,
where the finalizer would be inlined) is marked as `:nothrow`, it simply
bails out. However, even in such cases, we can insert a `finalize` call
at the end of the object’s lifetime, allowing us to call the finalizer
early if no exceptions occur.
This commit implements this optimization. To do so, it also moves
`finalize` to `Core`, so the compiler can handle it directly.
