* PPTC & Pool Enhancements.
* Avoid buffer allocations in CodeGenContext.GetCode(). Avoid stream allocations in PTC.PtcInfo.
Refactoring/nits.
* Use XXHash128, for Ptc.Load & Ptc.Save, x10 faster than Md5.
* Why not a nice Span.
* Added a simple PtcFormatter library for deserialization/serialization, which does not require reflection, in use at PtcJumpTable and PtcProfiler; improves maintainability and simplicity/readability of affected code.
* Nits.
* Revert #1987.
* Revert "Revert #1987."
This reverts commit 998be765cf7f7da5ff0c1c08de704c9012b0f49c.
