- EEClass has long had a concept of packable rarely accessed fields
- When we had NGEN we had logic to make these fields take very small amounts of space, but now that we no longer have NGEN, this code is not actually used in practice
- The unpacked form of these fields used 4 bytes per field, even though many of them were logically 2 byte fields
- The NumBoxed fields were just unnecessary, especially if we have a HasBoxedThreadStatics flag, which this change adds
- Move the HasBoxed flags to the WFLAGS_LOW_ENUM

Overall this saves 24 bytes per EEClass and moves all these fields onto a normal structure.

Co-authored-by: Austin Wise <AustinWise@gmail.com>

…ngen_thing_for_EEClass_fields

….com:davidwrighton/runtime into remove_special_ngen_thing_for_EEClass_fields