Remove relocations for vtable chunks (#17147)

Remove relocations for vtable chunks (#17147)

* Separate sections READONLY_VCHUNKS and READONLY_DICTIONARY

* Remove relocations for second-level indirection of Vtable in case FEATURE_NGEN_RELOCS_OPTIMIZATIONS is enabled.

Introduce FEATURE_NGEN_RELOCS_OPTIMIZATIONS, under which NGEN specific relocations optimizations are enabled

* Replace push/pop of R11 in stubs with
  - str/ldr of R4 in space reserved in epilog for non-tail calls
  - usage of R4 with hybrid-tail calls (same as for EmitShuffleThunk)

* Replace push/pop of R11 for function epilog with usage of LR as helper register right before its restore from stack