We should start planning for moving the foreign API from incubating modules back to java.base and mark it as preview.

Some initial considerations about where bits should go:

* create new package: java.foreign - and put most of the stuff there
* MemoryLayouts should disappear - Java layout constants should be moved in wrapper classes - other constants should be part of MemoryLayout
* MemoryHandles -> move to MethodHandles
* MemoryAccess -> consider renaming to MemorySegments