* Remove unused relaying XCM

* Aggregate HRMP (XCMP/HMP) messages. Payloads for spambot.

* Revert lock

* Fix

* Broken example

* Introduce fee payment mechanics into XCM.

* Weight limitations on XCM execution

* Mock environment for tests and the first test

* Tests for XCM and a few refactors.

* Remove code that's not ready

* Fix for an XCM and an additional test

* Query response system

* XCMP message dispatch system reimagining

- Moved most of the logic into xcm-handler pallet
- Altered the outgoing XCMP API from push to pull
- Changed underlying outgoing queue data structures to avoid multi-page read/writes
- Introduced queuing for incoming messages
- Introduced signal messages as a flow-control sub-stream
- Introduced flow-control with basic threshold back-pressure
- Introduced overall weight limitation on messages executed
- Additonal alterations to XCM APIs for the new system

* Some build fixes

* Remove the Encode bounds sprayed around

* More faff

* Fix bounds amek use latest scale codec.

* remove println

* fixes

* Fix XcmExecutor Tests

* Fix XCM bounds using derivative crate

* Refactor names of XcmGeneric &c into Xcm

* Repot the xcm-executor into xcm-builder

* Docs

* Docs

* Fixes

* Update xcm/src/lib.rs

Co-authored-by: Shawn Tabrizi <[email protected]>

* Fixes

* Docs

* Update runtime/parachains/src/ump.rs

Co-authored-by: Shawn Tabrizi <[email protected]>

* Docs

* Fixes

* Fixes

* Fixes

* Docs

* Fixes

* Fixes

* Introduce transfer_asset specialisation.

* Fixes

* Fixes

Co-authored-by: Shawn Tabrizi <[email protected]>

* Fungibles adapter and MultiLocation::X8

* Comments

* Comment & whitespace

* Fix up CI/CD for the new labels.

* Fix labels

* Whitespace

* Fixes

* Update Cargo.lock

* Update xcm/xcm-builder/src/fungibles_adapter.rs

Co-authored-by: Shawn Tabrizi <[email protected]>

Co-authored-by: Shawn Tabrizi <[email protected]>

* Replace undefined error in currency adapter.

* Update tranact asset errors.

* Update TransactAsset trait documentations.

* Update currency adapter error documentation.

* Add Xcm sender.

* Rename XCM sender and add description.

* Update copyright header.

Co-authored-by: Shawn Tabrizi <[email protected]>

* update tiny-keccak to 0.2

* update deps except bitvec and shared_memory

* fix some warning after futures upgrade

* remove useless package rename caused by bug in cargo-upgrade

* revert parity-util-mem *

* remove unused import

* cargo update

* remove all renames on parity-scale-codec

* remove the leftovers

* remove unused dep

* HRMP: Update the impl guide

* HRMP: Incorporate the channel notifications into the guide

* HRMP: Renaming in the impl guide

* HRMP: Constrain the maximum number of HRMP messages per candidate

This commit addresses the HRMP part of https://github.com/paritytech/polkadot/issues/1869

* XCM: Introduce HRMP related message types

* HRMP: Data structures and plumbing

* HRMP: Configuration

* HRMP: Data layout

* HRMP: Acceptance & Enactment

* HRMP: Test base logic

* Update adder collator

* HRMP: Runtime API for accessing inbound messages

Also, removing some redundant fully-qualified names.

* HRMP: Add diagnostic logging in acceptance criteria

* HRMP: Additional tests

* Self-review fixes

* save test refactorings for the next time

* Missed a return statement.

* a formatting blip

* Add missing logic for appending HRMP digests

* Remove the channel contents vectors which became empty

* Tighten HRMP channel digests invariants.

* Apply suggestions from code review

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

* Remove a note about sorting for channel id

* Add missing rustdocs to the configuration

* Clarify and update the invariant for HrmpChannelDigests

* Make the onboarding invariant less sloppy

Namely, introduce `Paras::is_valid_para` (in fact, it already is present
in the implementation) and hook up the invariant to that.

Note that this says "within a session" because I don't want to make it
super strict on the session boundary. The logic on the session boundary
should be extremely careful.

* Make `CandidateCheckContext` use T::BlockNumber for hrmp_watermark

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

Co-authored-by: Gavin Wood <[email protected]>

Co-authored-by: Gavin Wood <[email protected]>