Blocks without a terminator are not handled correctly by
`Block::without_terminator`: the last operation is excluded, even when
it is not a terminator. With this commit, only terminators are excluded.
If the last operation is unregistered, it is included for safety.

We can use *Set::insert_range to collapse:

  for (auto Elem : Range)
    Set.insert(E);

down to:

  Set.insert_range(Range);

In some cases, we can further fold that into the set declaration.

DenseSet, SmallPtrSet, SmallSet, SetVector, and StringSet recently
gained C++23-style insert_range.  This patch replaces:

  Dest.insert(Src.begin(), Src.end());

with:

  Dest.insert_range(Src);

This patch does not touch custom begin like succ_begin for now.

This PR attempts to consolidate the different topological sort utilities
into one place. It adds them to the analysis folder because the
`SliceAnalysis` uses some of these.

There are now two different sorting strategies: 
1. Sort only according to SSA use-def chains
2. Sort while taking regions into account. This requires a much more
elaborate traversal and cannot be applied on graph regions that easily.

This additionally reimplements the region aware topological sorting
because the previous implementation had an exponential space complexity.

I'm open to suggestions on how to combine this further or how to fuse
the test passes.