Fix DescriptorUtils#getContainingModule
Fix most of the missing visibilities in stdlib

Specify visibilities and reformat surrounding code
Add test checking that there is no internal visibility specified in stdlib sources
Internal visibility does not make sense in stdlib
because it is either missed public or private would be more appropriate
Stdlib minor: Make kotlin.support.State enum
Stdlib minor: Remove unused AbstractIterator#peek()
Stdlib minor: Remove unused ChangeEvent#propogationId