#79811)

* [mono][llvm] Added a null-check for 2-dim array accessors, addressing #79022

* [mono][llvm] Adding a regression test for issue #79022

* [mono][llvm] Null check for 2D arrays is now more DRY.

* [mono][llvm] Null-checking on 2D array access, removed restriction to LLVM.

The DacValidateMD is not resilient to invalid MethodDesc that contains
NULL in its m_pMethTab field. It was found when using the ClrMD in the
BenchmarkDotNet disassembler code which is trying to find if some constants
in the code represent MethodDesc so that it can dump the related method
name.

This change fixes it by checking the MethodTable after it is extracted
from the MethodDesc. There are two values that are not translated between
the target and the debugger sides - NULL and -1. So I have added handling
both as invalid there.

Fixes #79654

* Instead of jitting interp_entry wrappers for every entry point, record a hit count for each one and then queue it for JIT compilation once it's hit enough times
* Add prefs controlling interp entry queue thresholds
* Add support for using imported globals for pointer constants (to enable future threading/caching), off by default
* Use base 36 for jiterpreter import names to save space

Code inside a `#ifdef DEBUG` had a side-effect not visible to
Release builds. Pull that code out of the `#ifdef`.

Fixes #79560

* Fix build for DUMP_GC_TABLES defined in Release

* Formatting