remove `AllSubsystems` and `AllSubsystemsGen` types (#3874)

* introduce the OverseerConnector, use it

* introduce is_relay_chain to RelayChainSelection

* Update node/service/src/lib.rs

Co-authored-by: Andronik Ordian <[email protected]>

* avoid the deferred setting of `is_relay_chain` in `RelayChainSelection`

* positive assertion is not mandated, only the negative one, to avoid a stall

* cleanup: overseer residue

* spellcheck

* fixin

* groundwork to obsolete Overseer::new and AllSubsystemsGen proc-macro

* Now all malus & tests can be ported to the builder pattern.

Obsoletes `Overseer::new`, `AllSubsystemsGen` derive macro, `AllSubsystems`.

* spellcheck

* adjust tests, minor fixes

* remove derive macro AllSubsystemsGen

* add forgotten file dummy.rs

* remove residue

* good news everyone!

* spellcheck

* address review comments

* fixup imports

* make it conditional

* fixup docs

* reduce import

* chore: fmt

* chore: fmt

* chore: spellcheck / nlprules

* fixup malus variant-a

* fmt

* fix

* fixins

* pfmt

* fixins

* chore: fmt

* remove expanded overseer generation

* tracing version

* Update node/network/statement-distribution/src/lib.rs

Co-authored-by: Robert Habermeier <[email protected]>

* use future::ready instead

* silence warning

* chore: fmt

Co-authored-by: Andronik Ordian <[email protected]>
Co-authored-by: Robert Habermeier <[email protected]>