feat(Runtime): Refund allowance to the access keys

[evgenykuzyakov]

Fixes: #2523

This PR introduces access keys allowance refunds using the old Receipt refund data structure by reusing existing fields.

Right now the refund receipt is identified by a receipt with the predecessor_id == "system". These are special type of receipts that don't cost any gas and also don't generate refunds themselves.

This change reuses existing fields from the ActionReceipt such as signer_id and signer_public_key to distinguish between Gas Refunds and Deposit Refunds.
Gas refunds are refunds for the unused amount of Gas, while the Deposit Refunds are for the deposit amounts attached to transfer and function_call actions as well as refund for an action of deleting the account.

New Gas Refund Receipts also have the predecessor_id == "system", but signer_id == receiver_id (because gas refunds always sent to the signer). While Deposit refunds still have signer_id == "system". This allows to distinguish between Gas vs Deposit refunds.

The Gas Refund also uses the original signer_public_key to be able to identify the access key needed to refund the unused gas potion of the allowance.

When the Gas refund receipt arrives to the account, the original access key that signed the transaction that spawned this receipt might have been changed (e.g. using delete_key/add_key). This means that in some situation the gas refund towards the allowance can't be made, so we use best effort to refund the allowance, even if the access key is different.

• TODO: Spec update

Spec update: near/NEPs#75

Test plan

• Modified the test that covers function call access key and verified that it generated the refund.
• CI

[gitpod-io]

[bowenwang1996]

Please don't forget to bump protocol version.

[bowenwang1996]

Epic 🚀