pallet-whitelist: E2E Test Deferred Dispatch

[runcomet]

Summary

Closes #594

Adds E2E test coverage for the pallet-whitelist deferred dispatch feature on Kusama Asset Hub (and by extension Polkadot Asset Hub). Deferred dispatch allows whitelisted calls to be executed later with a signed origin after an initial Root dispatch creates a deferred entry.

Test Coverage

Success Path (5 tests)

Test	What it verifies
happy path	Full flow: defer → whitelist → signed execution
direct dispatch	Already-whitelisted call executes immediately without deferral
root semantics	Signed execution runs the inner call with Root origin
hash-only dispatch	dispatchWhitelistedCall (without preimage) variant works
permissionless removal	Anyone can remove an expired deferred entry

Failure Path (5 tests)

Test	What it verifies
already deferred	Duplicate deferral is rejected
invalid weight witness	Wrong call weight is rejected
origin gating	Non-Root whitelist/dispatch is rejected
call already whitelisted	Duplicate whitelist is rejected
remove whitelisted call	BadOrigin / double-remove is rejected

Runtime Prerequisites

The deferred dispatch feature requires pallet-whitelist with the deferred-dispatch feature enabled in the target runtime. To enable it:

1. Add pallet-whitelist to your runtime with this feature

In your runtime's Cargo.toml:

[dependencies]
pallet-whitelist = { path = "pallets/whitelist", default-features = false }

2. Configure existing runtime configs to include BlockNumberProvider and DeferredDispatchExpiration

impl pallet_whitelist::Config for Runtime {
    ...
    type DeferredDispatchExpiration = ConstU32<{ 15 * RC_MINUTES }>;
    type BlockNumberProvider = RelaychainDataProvider<Runtime>;
}

3. Build the WASM

cargo build --release -p asset-hub-kusama-runtime &&
cargo build --release -p asset-hub-polkadot-runtime

4. Test

ASSETHUBKUSAMA_WASM=.../asset_hub_kusama_runtime.compact.wasm \
bun run test packages/kusama/src/assetHubKusama.whitelist.deferred.e2e.test.ts -- --run

[runcomet]

please review @rockbmb @dhirajs0

[rockbmb]

@runcomet will take a look next week!

[github-actions]

The changes look good and the tests are comprehensive. I've found a couple of opportunities to improve type safety in the new shared test file by replacing any with more specific types from Polkadot.js.

[rockbmb]

@runcomet apologies for the delay; could you merge master into this, and refactor this suite to use the new pattern of client-sharing across test suites introduced in #609 ?