In preparation of loop unrolling, we move some loop analysis
infrastructure out of loop-peeling.{h, cc}, and implement some
additional required functionality.

Changes:
- Implement inner_loops() in loop-analysis.h. Change some parameters
  in other functions from Loop* to (const Loop*) to accommodate this
  change.
- Move Peeling class into loop-analysis, rename it to NodeCopier.
- Simplify NodeCopier::CopyNodes().
- Allow NodeCopier to produce multiple copies of the targeted Nodes.
- Introduce LoopFinder::HasMarkedExits(). Move the implementation of
  LoopPeeling::CanPeel() there. CanPeel() is now an alias for
  HasMarkedExits().

Bug: v8:11298
Change-Id: I245b2e937393e4a78ce4d355e1290aaf6e617114
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2672019
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72555}