karura native asset test

[zqhxuyuan]

current we have karura transfer BNC to bifrost test and vice versa, but missing karura transfer KAR to bifrost test and vice versa. we need this test because in new reanchor, if bifrost transfer KAR to karura, the reanchored location will be (0, GeneralIndex(KAR)).

Acala/runtime/integration-tests/src/relaychain/kusama_cross_chain_transfer.rs

Lines 103 to 106 in 6345f24

	Karura::execute_with(|| {
	assert_ok!(XTokens::transfer(
	Origin::signed(ALICE.into()),
	BNC,

if just change token and network, there'll be TooExpensive because in the Bifrost, the KAR is setting to (1, X2(2001, KAR)) however the asset of KarPerSecond is (1, X2(2000, KAR)). the reason is we're using same Runtime for Karura and Sibling network but also with same CurrencyIdConvert.