* on-demand headers relay

* bool::then

* move file

* atomic submit_signed_extrinsic

* remove cli options from future

* test on-demand relay

* TODOs

* fixed initialization call for Westend -> Millau

* Update relays/client-substrate/src/client.rs

Co-authored-by: Hernando Castano <[email protected]>

* removed on_demand_headers_relay.rs

* on_demand_headers_relay traces

* fix compilation

* fmt

* docs

Co-authored-by: Hernando Castano <[email protected]>

* slightly changed relay loop initialization

* git mv

* clippy

* more clippy

* loop_run -> run_loop

* review and clippy

* clippy

* Remove chains.

* Move relay clients.

* Flatten generic.

* Fix fmt.