Service various cleanups (#3238)

* Remove generic from sign()

* Remove mandatory RuntimeGenesis trait req

* Remove requirement from Configuration

* Relax trait bounds of core/cli

* Move method

* The config field is no longer public

* Remove Components from bounds of functions

* Implement DerefMut for LightComponents

* Implement Executor for Full/LightComponents

* Fix bad merge

* Fix forgotten config()

* Fix build