with free intervals (instead of fixed free headers) we need to check `improved_by` from extension code

make FreeHeadersRemaining an Option => we know that when we are outside of tx body, it is `None` and otherwise it is `Some`

added WeightInfoExt for pallet-bridge-grandpa to include extra wight coming from CheckAndBoostBridgeGrandpaTransactions

added CheckAndBoostBridgeGrandpaTransactions that checks whether bridge GRANDPA transactions are obsolete and, if not, it may apply priority boost to

check_obsolete_submit_finality_proof may now boost transaction priority (this is not used yet - see next commit)

move grandpa call result check from RefundTransactionExtensionAdapter to RefundBridgedGrandpaMessages

added is_free_execution_expected parameter to the submit_finality_proof_ex + check it from the transaction extension