Dynamic generic dictionary expansion feature (#32270)

Dynamic generic dictionary expansion feature (#32270)

* Dynamic dictionary expansion feature

1) Separate dictionary layout expansion from dictionary expansions on types and methods
2) Dictionary expansions on types and methods done on-demand (if needed), after size checks by codegen (uses new JIT feature)
3) Update the R2R dictionary access stubs to perform size checks (and major cleanup there)
4) Add unit test
5) Update documentation
6) Update JIT interface guid