[Runtime][Relay][Cleanup] Clean up for memory pass to enable heterogenous execution support. (#5324)

* Cleanup type pack and unpack for tuples.

* Clean up the memory_pass using common helpers

* Clean up memory.cc

* Refactor pass

* Add doc strings

* Fix CPPlint

* Fix PyLint

* Fix

* Apply suggestions from code review

Co-Authored-By: Zhi <5145158+zhiics@users.noreply.github.com>

* Fix typo

Co-authored-by: Zhi <5145158+zhiics@users.noreply.github.com>