Experimental: Optimize internal ValueStack by introducing a `ValueS…

…tackPtr` type (#688)

* merge imports in executor

* optimize ValueStackRef

* remove lifetime from ValueStackPtr and simplify API

* fix internal docs

* fix clippy suggestion

* renamed some methods

* add repr(transparent)

* maybe fix miri

* fix internal doc links

* add some inline annotations

* add missing inline annotation

* make Executor use ValueStackPtr directly

* reverse some of the changes of last commit

* add inline annotations

* simplify ValueStack::stack_ptr

* optimize sync_stack_ptr

* implement ValueStack::stack_ptr in terms of base_ptr

* fix internal doc links

* rename vref moduel to sp

* simplify ValueStackPtr

* move value_stack field

* apply rustfmt and clippy suggestions

* add ValueStackPtr::push_as method

* cleanup

* refactor ValueStackPtr::drop_keep impl

* improve ValueStackPtr::drop_keep performance

* optimize drop keep impl

* add inline annotations

* try out optimization for pop2 and pop3

* Revert "try out optimization for pop2 and pop3"

This reverts commit 79bb0d1.

* try out different impl for ValueStackPtr::set

* add more inline annotations

* experiment: use references instead of by value

* Revert "experiment: use references instead of by value"

This reverts commit fe594f9.

* experiment with ValueStackPtr::pop

* Revert "experiment with ValueStackPtr::pop"

This reverts commit 555f601.

* make use of pop2 in pop3

* move method arounds

* try to optimize some ValueStackPtr methods

* add ValueStackPtr::drop

* fix internal doc links

* add missing docs

* add some inline annotations

* add experimental inline annotations

* experimental opt for drop_keep

* experimental opt for drop_keep (take 2)

* partially revert some recent changes

* experimental revert some more changes

* experimental change

* tryout optimization in drop_keep

* Revert "tryout optimization in drop_keep"

This reverts commit ad25645.

* opt attept #19283

* another opt attempt

* move method

* try out opt

* Revert "try out opt"

This reverts commit 8954060.