make remote-ext work with ws and safe RPCs (#8889)

* make remote-ext work with ws and safe RPCs

* Update docs.

* Update utils/frame/remote-externalities/Cargo.toml

Co-authored-by: Niklas Adolfsson <[email protected]>

* Fix test

* Update lock file

* Update utils/frame/remote-externalities/src/lib.rs

Co-authored-by: Bastian Köcher <[email protected]>

* Fix build again.

* revert lifetime stuff

Co-authored-by: Niklas Adolfsson <[email protected]>
Co-authored-by: Bastian Köcher <[email protected]>