try-runtime-cli: 'instant' snapshots, threading refactor, better progress logs (#14057)

* remote externalities refactor

* remove redundant logs

* use const for parallel requests

* prefer functional

* improve variable naming

* handle requests error

* use overlayedchanges

* Revert "use overlayedchanges"

This reverts commit c0ddb87a5abdd52207597f5df66cbbdf9d79badc.

* Revert "Revert "use overlayedchanges""

This reverts commit 1d49362d9b999c045c8f970a0ab8b486bc47a90a.

* Revert "Revert "Revert "use overlayedchanges"""

This reverts commit 06df786488d94f249e9abccffac4af445f76e5a7.

* backup/load raw storage values

* test raw storage drain and restore

* update snapshot tests

* improve logs

* clippy suggestions

* address comments

* fix example

* fix test

* clippy