* send_message should not return an error

* Apply suggestions from code review

Co-authored-by: Peter Goodspeed-Niklaus <[email protected]>

* s/send_logging_error/send_and_log_error

Co-authored-by: Peter Goodspeed-Niklaus <[email protected]>

* Change SpawnedSubsystem type to log subsystem errors

* Remove clone

* Make `AllSubsystems` usage easier in tests

This makes the usage of `AllSubsystems` easier in tests by introducing
new methods.

- `dummy` initializes `AllSubsystems` with all systems set to dummy
- `replace_*` to replace any subsystem

Besides that this pr adds a `ForwardSubsystem` that is also useful for
tests. This subsystem will forward all incoming messages to the given channel.

* Update node/overseer/src/lib.rs

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

* Update node/subsystem/src/lib.rs

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

* Update node/subsystem/src/lib.rs

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

* Move ForwardSubsystem and add a test

* Break some lines

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

* WIP

* The initial implementation of the collator side.

* Improve comments

* Multiple collation requests

* Add more tests and comments to validator side

* Add comments, remove dead code

* Apply suggestions from code review

Co-authored-by: Peter Goodspeed-Niklaus <[email protected]>

* Fix build after suggested changes

* Also connect to the next validator group

* Remove a Future impl and move TimeoutExt to util

* Minor nits

* Fix build

* Change FetchCollations back to FetchCollation

* Try this

* Final fixes

* Fix build

Co-authored-by: Peter Goodspeed-Niklaus <[email protected]>

* jobs: don't early exit when there are no jobs

* utils: fix merged test

* utils: less verbose

* utils: add an assert subsystem is running

* utils: use TimeoutExt from test-helpers

* test-helpers: use TimeoutExt

* start sketching out a collation generation subsystem

* invent a basic strategy for double initialization

* clean up warnings

* impl util requests from runtime assuming a context instead of a FromJob sender

* implement collation generation algorithm from guide

* update AllMessages in tests

* fix trivial review comments

* remove another redundant declaration from merge

* filter availability cores by para_id

* handle new activations each in their own async task

* update guide according to the actual current implementation

* add initialization to guide

* add general-purpose subsystem_test_harness helper

* write first handle_new_activations test

* add test that handle_new_activations filters local_validation_data requests

* add (failing) test of collation distribution message sending

* rustfmt

* broken: work on fixing sender test

Unfortunately, for reasons that are not yet clear, despite the public key
and checked data being identical, the signer is not producing an identical
signature. This commit produces this output (among more):

signing with  Public(c4733ab0bbe3ba4c096685d1737a7f498cdbdd167a767d04a21dc7df12b8c858 (5GWHUNm5...))
checking with Public(c4733ab0bbe3ba4c096685d1737a7f498cdbdd167a767d04a21dc7df12b8c858 (5GWHUNm5...))
signed payload:  [4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 10, 0, 0, 0, c7, e5, c0, 64, 7a, db, fe, 44, 81, e5, 51, 11, 79, 9f, a5, 63, 93, 94, 3c, c4, 36, c6, 30, 36, c2, c5, 44, a2, 1b, db, b7, 82, 3, 17, a, 2e, 75, 97, b7, b7, e3, d8, 4c, 5, 39, 1d, 13, 9a, 62, b1, 57, e7, 87, 86, d8, c0, 82, f2, 9d, cf, 4c, 11, 13, 14]
checked payload: [4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 10, 0, 0, 0, c7, e5, c0, 64, 7a, db, fe, 44, 81, e5, 51, 11, 79, 9f, a5, 63, 93, 94, 3c, c4, 36, c6, 30, 36, c2, c5, 44, a2, 1b, db, b7, 82, 3, 17, a, 2e, 75, 97, b7, b7, e3, d8, 4c, 5, 39, 1d, 13, 9a, 62, b1, 57, e7, 87, 86, d8, c0, 82, f2, 9d, cf, 4c, 11, 13, 14]

* fix broken test

* collation function returns commitments hash

It doesn't look like we use the actual commitments data anywhere, and
it's not obvious if there are any fields of `CandidateCommitments`
not available to the collator, so this commit just assigns them the
entire responsibility of generating the hash.

* add missing overseer impls

* calculating erasure coding is polkadot's responsibility, not cumulus

* concurrentize per-relay_parent requests

* subsystem: add spawn_blocking to SubsystemContext

* candidate-validation: use spawn_blocking for exhaustive tasks

Closes #1237

* break out subsystem-util and subsystem-test-helpers into individual crates

* cause all packages to check successfully