Generate large messages (#700)

* generate large messages

* consider headers sync lag when computing number of rewards in confirmation

* more fixes

* fix logs

* fix warnings

* do not wait until tx that has delivered nonces will be finalized before submitting other tx

* tests for maximal weight/size

* cleanup

* cleanup

* clippy

* compilation

* args for dispatch weight and remark size

* ExplicitOrMaximal

* clippy