Snowbridge Headers on Demand (polkadot-fellows#365)

Upgrades Snowbridge to have a much more cost effective Ethereum light
client. In the current light client in production, all Ethereum
execution headers are stored, whether they contain a transfer message or
not. This PR upgrades Snowbridge to not store execution headers at all,
but provide the execution header proof alongside a message. Ethereum
beacon headers are still stored, to track finalized headers and do
ancestry proofs.

More details on the change on the original PR:
paritytech/polkadot-sdk#3761

---------

Co-authored-by: Branislav Kontur <[email protected]>

CHANGELOG.md

@@ -9,6 +9,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Changed
 
 - Polkadot chains: allow arbitrary XCM execution ([polkadot-fellows/runtimes#345](https://github.com/polkadot-fellows/runtimes/pull/345))
+- Snowbridge: Sync headers on demand ([polkadot-fellows/runtimes#345](https://github.com/polkadot-fellows/runtimes/pull/365))
 
 ## [1.2.7] 14.06.2024
 

Cargo.toml

@@ -189,17 +189,17 @@ separator = { version = "0.4.1" }
 serde = { version = "1.0.196" }
 serde_json = { version = "1.0.113" }
 smallvec = { version = "1.13.1" }
-snowbridge-beacon-primitives = { version = "0.1.0", default-features = false }
-snowbridge-core = { version = "0.1.1", default-features = false }
+snowbridge-beacon-primitives = { version = "0.1.2", default-features = false }
+snowbridge-core = { version = "0.1.3", default-features = false }
 snowbridge-outbound-queue-runtime-api = { version = "0.1.1", default-features = false }
-snowbridge-pallet-ethereum-client = { version = "0.1.2", default-features = false }
-snowbridge-pallet-inbound-queue = { version = "0.1.1", default-features = false }
-snowbridge-pallet-inbound-queue-fixtures = { version = "0.9.0" }
+snowbridge-pallet-ethereum-client = { version = "0.1.3", default-features = false }
+snowbridge-pallet-inbound-queue = { version = "0.1.3", default-features = false }
+snowbridge-pallet-inbound-queue-fixtures = { version = "0.9.1" }
 snowbridge-pallet-outbound-queue = { version = "0.1.1", default-features = false }
 snowbridge-pallet-system = { version = "0.1.1", default-features = false }
 snowbridge-router-primitives = { version = "0.1.0", default-features = false }
 snowbridge-runtime-common = { version = "0.1.0", default-features = false }
-snowbridge-runtime-test-common = { version = "0.1.0" }
+snowbridge-runtime-test-common = { version = "0.1.2" }
 snowbridge-system-runtime-api = { version = "0.1.0", default-features = false }
 sp-api = { version = "27.0.1", default-features = false }
 sp-application-crypto = { version = "31.0.0", default-features = false }