Take send cost on BH into account

[yrong]

Context

This PR tries to fix the issue that send cost on BH is not taken into account, should be included and match the deliveryCost on Ethereum.

Resolves: https://linear.app/snowfork/issue/SNO-980

Resolves: https://linear.app/snowfork/issue/SNO-1115

[yrong]

Add a runtime test calculate the delivery cost:

cargo test -p bridge-hub-rococo-runtime --test snowbridge fetch_delivery_cost -- --nocapture
inbound_delivery_cost:1000092265984
inbound_send_cost:104766618
outbound_delivery_cost:16903333

As result above shows inbound_send_cost consumes a tiny portion of the total(<0.1%) which can be ignored, so this PR seems unnecessary.

[vgeddes]

Hey Ron, excuse the tardy response on this, I was mostly OOTO last week.

Yeah, I was initially aware that XCM sends could have a send cost, but when I looked at the runtime config these costs seemed to be zero, so I avoided having to implement it.

Do you know how these send costs are configured and calculated in the xcm executor?

[vgeddes]

As result above shows inbound_send_cost consumes a tiny portion of the total(<0.1%) which can be ignored, so this PR seems unnecessary.

Lets add a linear ticket for this, so we can track it when scheduling priorities.

[yrong]

how these send costs are configured and calculated in the xcm executor?

For sending xcm to sibling chains the cost is calculated with

polkadot-sdk/cumulus/pallets/xcmp-queue/src/lib.rs

Line 916 in 3f495e5

let price = T::PriceForSiblingDelivery::price_for_delivery(id, &xcm);

Add a ticket for tracing in https://linear.app/snowfork/issue/SNO-980

[vgeddes]

Reopening this, even though its low priority. Otherwise we may delete the branch by mistake.

[alistair-singh]

Nice catch!

[alistair-singh]

Instead of configuring an XCM here to set the fee, I would prefer we use a constant fee and then in a test assert that the const equates to the xcm so we know if when the fee diviates.

[yrong]

8ad87ba

[alistair-singh]

We should probably assert that the configured cost is greater than or equal to the xcm cost using the same method you used here:

8ad87ba#diff-832917c2fd6302a9f175210f7d9941ea82a1a7c5a35aa35e662380074d405203L370-L377

Probably not important for this test. But may be very important for the fellowship runtime.

[yrong]

4012a59