Feat/oauth mvp test (#93)

* Implement ERC20 functions.

* Add test cases that's not implemented yet.

* Update _execute function.
If caller calls another function which is not a basic ERC20 function, _execute allows user's action.

* Update _checkAllowanceReduction.
It checks the difference between amount in callData and tokenAmount

* Add return line into _execute function.

* Simplify Wallet and add failing test cases

* Feat/oauth mvp allowance (#88)

* Implement ERC20 functions.

* Add test cases that's not implemented yet.

* Update _execute function.
If caller calls another function which is not a basic ERC20 function, _execute allows user's action.

* Update _checkAllowanceReduction.
It checks the difference between amount in callData and tokenAmount

* Add return line into _execute function.

* Simplify Wallet and add failing test cases

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Co-authored-by: SoraSuegami <suegamisora@gmail.com>

* Modify subject templates for oauth.

* Fix _parseSigninSubjectParams and add test cases into OauthExtensionCommandTest.

* Add revert test cases.

* Fix tests

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Co-authored-by: SoraSuegami <suegamisora@gmail.com>