`follow-chain` testing mode for try-runtime (and revamp CLI configs). (#9788)

* deadlock, need to ask someone to help now

* Finally it seems to be working.. at least for a few blocks

* self-review

* major mega revamp

* some small fixes

* another mega refactor

* add license

* Apply suggestions from code review

* hack around signature verification

* Some fixes

* Update utils/frame/try-runtime/cli/src/lib.rs

Co-authored-by: Zeke Mostov <[email protected]>

* Update utils/frame/try-runtime/cli/src/lib.rs

Co-authored-by: Zeke Mostov <[email protected]>

* Update utils/frame/try-runtime/cli/src/lib.rs

Co-authored-by: Zeke Mostov <[email protected]>

* final tweaks, hopefully.

* a little self-review

* Add the ext root check

Co-authored-by: Zeke Mostov <[email protected]>