Fee currencies without `credit`/`debit`

[palango]

Description

Prototype for gas currency payments without credit/debit functions in the token contract.

Inside the EVM state transition code it is possible to send transactions from arbitrary accounts. @karlb came up with the idea to use this to use the existing approve/transferFrom functions to remove the need of credit/debit functions in fee currency token contracts.

During the implementation it became clear that it is possible to just call transfer, which reduces the overhead further.

There's two remaining differences from the current implementation:

• This will emit transfer events. It should be possible to discard them though.
• It doesn't temporarily reduce the total supply like we do now. It still keeps the invariant "sum(balances) == total supply" by moving the tokens to 0xce106a5 instead of letting the debited fees vanish.

⚠️ The code is a prototype, the gas limit handling is just wrong and error handling needs to be improved.

[github-actions[bot]]

Test failures:
TestTransferERC20: e2e_test Checking getExchangeSpenders. spenders = [0x000000000000000000000000000000000000d028] Checking medianRate. numerator = 1000000000000000000000000 denominator = 1000000000000000000000000 Checking gas price minimum. cusdValue = 100000000 e2e_transfer_test.go:472:
TestRPCDynamicTxGasPriceWithoutStateForAlternativeCurrencyBeforeGingerbread: e2e_test Checking getExchangeSpenders. spenders = [0x000000000000000000000000000000000000d028] Checking medianRate. numerator = 1000000000000000000000000 denominator = 1000000000000000000000000 Checking gas price minimum. cusdValue = 100000000 e2e_test.go:607:
TestRPCDynamicTxGasPriceWithoutStateForAlternativeCurrencyAfterGingerbread: e2e_test Checking getExchangeSpenders. spenders = [0x000000000000000000000000000000000000d028] Checking medianRate. numerator = 1000000000000000000000000 denominator = 1000000000000000000000000 Checking gas price minimum. cusdValue = 100000000 e2e_test.go:607:
TestEthersJSCompatibilityDisableAfterGingerbread: e2e_test Checking getExchangeSpenders. spenders = [0x000000000000000000000000000000000000d028] Checking medianRate. numerator = 1000000000000000000000000 denominator = 1000000000000000000000000 Checking gas price minimum. cusdValue = 100000000 Checking getExchangeSpenders. spenders = [0x000000000000000000000000000000000000d028] Checking medianRate. numerator = 1000000000000000000000000 denominator = 1000000000000000000000000 Checking gas price minimum. cusdValue = 100000000 e2e_test.go:742: e2e_test.go:744:
TestEthersJSCompatibilityDisableBeforeGingerbread: e2e_test Checking getExchangeSpenders. spenders = [0x000000000000000000000000000000000000d028] Checking medianRate. numerator = 1000000000000000000000000 denominator = 1000000000000000000000000 Checking gas price minimum. cusdValue = 100000000 e2e_test.go:770: Checking getExchangeSpenders. spenders = [0x000000000000000000000000000000000000d028] Checking medianRate. numerator = 1000000000000000000000000 denominator = 1000000000000000000000000 Checking gas price minimum. cusdValue = 100000000
This test report was produced by the test-summary action.  Made with ❤️ in Cambridge.

[palango]

Closing, as this will be Cel2 only.