Adds availability-write regression tests.
The results for the `availability-distribution` subsystem are volatile,
so I had to reduce the precision of the test.

Another simple refactory to prune some duplicate code

Follow up of: https://github.com/paritytech/polkadot-sdk/pull/3684

Devs seem to not realize that this should be filled out manually. The
default is also often wrong.

https://github.com/paritytech/polkadot-sdk/issues/3742

Related to
https://github.com/paritytech/parity-bridges-common/issues/2538

This PR doesn't contain any functional changes. 

The PR moves specific bridged chain definitions from
`bridges/primitives` to `bridges/chains` folder in order to facilitate
the migration of the `parity-bridges-repo` into `polkadot-sdk` as
discussed in https://hackmd.io/LprWjZ0bQXKpFeveYHIRXw?view

Apart from this it also includes some cosmetic changes to some
`Cargo.toml` files as a result of running `diener workspacify`.

cc https://github.com/paritytech/ci_cd/issues/943

Fixes https://github.com/paritytech/polkadot-sdk/issues/3762 .

---------

Co-authored-by: eskimor <eskimor@no-such-url.com>
Co-authored-by: Adrian Catangiu <adrian@parity.io>

Currently `transfer_assets` from pallet-xcm covers 4 main different
transfer types:
- `localReserve`
- `DestinationReserve`
- `Teleport`
- `RemoteReserve`

For the first three, the local execution and the remote message sending
are separated, and fees are deducted in pallet-xcm itself:
https://github.com/paritytech/polkadot-sdk/blob/3410dfb3

/polkadot/xcm/pallet-xcm/src/lib.rs#L1758.

For the 4th case `RemoteReserve`, pallet-xcm is still relying on the
xcm-executor itself to send the message (through the
`initiateReserveWithdraw` instruction). In this case, if delivery fees
need to be charged, it is not possible to do so because the
`jit_withdraw` mode has not being set.

This PR proposes to still use the `initiateReserveWithdraw` but
prepending a `setFeesMode { jit_withdraw: true }` to make sure delivery
fees can be paid.

A test-case is also added to present the aforementioned case

---------

Co-authored-by: Adrian Catangiu <adrian@parity.io>

We do not need to make these traits generic over QueryId type, we can
just use the QueryId alias everywhere

Make sure explicitly set by the operator public addresses go first in
the authority discovery DHT records.

Also update `Discovery` behavior to eliminate duplicates in the returned
addresses.

This PR should improve situation with
https://github.com/paritytech/polkadot-sdk/issues/3519.

Obsoletes https://github.com/paritytech/polkadot-sdk/pull/3657.

Bridging fees are calculated using a static ETH/DOT exchange rate that
can deviate significantly from the real-world exchange rate. We
therefore need to add a safety margin to the fee so that users almost
aways cover the cost of relaying.

# FAQ

> Why introduce a `multiplier` parameter instead of configuring an
exchange rate which already has a safety factor applied?

When converting from ETH to DOT, we need to _divide_ the multiplier by
the exchange rate, and to convert from DOT to ETH we need to _multiply_
the multiplier by the exchange rate.

> Other input parameters to the fee calculation can also deviate from
real-world values. These include substrate weights, gas prices, and so
on. Why does the multiplier introduced here not adjust those?

A single scalar multiplier won't be able to accommodate the different
volatilities efficiently. For example, gas prices are much more volatile
than exchange rates, and substrate weights hardly ever change.

So the pricing config relating to weights and gas prices should already
have some appropriate safety margin pre-applied.

# Detailed Changes:

* Added `multiplier` field to `PricingParameters`
* Outbound-queue fee is multiplied by `multiplier`
* This `multiplier` is synced to the Ethereum side
* Improved Runtime API for calculating outbound-queue fees. This API
makes it much easier to for configure parts of the system in preparation
for launch.
* Improve and clarify code documentation

Upstreamed from https://github.com/Snowfork/polkadot-sdk/pull/127

---------

Co-authored-by: Clara van Staden <claravanstaden64@gmail.com>
Co-authored-by: Adrian Catangiu <adrian@parity.io>