During inlining, some instructions in the caller may be deleted. So
when publishing this best effort list of instructions which were
"changed" during inlining, don't start from a deleted instruction.
Instead just don't publish, as already happens in other cases.
Without actually addressing
```
// TODO: get a list of cloned instructions from the `inlineFunction`
```
this is somewhat better than checking for having reached the end of the
function during the walk because that will result in falsely
broadcasting that some unchanged instructions have changed whereas this
change only results in not broadcasting which is already being done in
some cases (e.g. when a `begin_apply` is immediately followed by an
`end_apply`).
During inlining, the apply is deleted. So when publishing this best
effort list of which instructions were "changed" during inlining, start
from the instruction before the deleted apply.
* move some Cloner utilities from ContextCommon.swift directly into Cloner.swift
* add an `cloneRecursively` overload which doesn't require the `customGetCloned` closure argument
* some small cleanups
