JIT: add OSR patchpoint strategy, inhibit tail duplication (#66208)

JIT: add OSR patchpoint strategy, inhibit tail duplication (#66208)

Two changes for OSR:
* add new strategies for placing patchpoints -- either at
  backedge sources (instead of targets) or adaptive. depending
  on number of backedges. Change default to adaptive, since this
  works better with the flow we see from C# `for` loops.
* inhibit tail duplication for OSR as it may end up interfering
  with loop recognition.

We may not be able to place patchpoints at sources, for various reasons;
if so we fall back to placing them at targets.

We also can't place patchpoints unless block entries are also stack empty
ponts. This means forgoing patchpoints in some IL cases..