feat: add custom reward token to permit

[rndquu]

Related to #16

This PR adds support for custom ERC20 token address in permits. So instead of hardcoding ERC20 reward token address partners will have to set it manually.

How it is expected to work:

1. Partner sets a config for the conversation-rewards plugin similar to:

- uses:
      - plugin: ubiquibot/conversation-rewards
        type: github
        with:
          evmNetworkId: 100
          evmPrivateEncrypted: "kmpTKq5Wh9r9x5j3U9GqZr3NYnjK2g0HtbzeUBOuLC2y3x8ja_SKBNlB2AZ6LigXHP_HeMitftVUtzmoj8CFfVP9SqjWoL6IPku1hVTWkdTn97g1IxzmjydFxjdcf0wuDW1hvVtoq3Uw5yALABqxcQ"
          erc20RewardToken: "0xe91D153E0b41518A2Ce8Dd3D7944Fa863463a97d" # WXDAI

2. On permit generation in the conversation-rewards plugin here ERC20 reward token address will be read from the config and passed in permit requests

Notice:

• The package version is bumped from 1.2.2 to 1.2.3 although ideally it should be bumped to 2.0.0 since backwards compatibility for the generatePayoutPermit() is broken
• I'm not sure if this PR breaks some other plugins
• The next step is to update https://github.com/ubiquibot/conversation-rewards to use the updated generateErc20PermitSignature() method

[Keyrxng]

tests passing and looks good

also afaik it doesn't break any other plugins

[gentlementlegen]

This should not break any plugin since plugins will use a specific version of the package, meaning they won't be using it with the changes here, unless we update the version within their package.json.

[gentlementlegen]

@rndquu fine with the content. I just think you might want to amend the commit to change feat to feat! as this contains breaking changes.

[rndquu]

@rndquu fine with the content. I just think you might want to amend the commit to change feat to feat! as this contains breaking changes.

As far I understand the changes introduced in this PR touch only the conversation-rewards plugin which I'll update to reflect the changes in this PR. Since all of the plugins are under active development I think it's ok to update the version to 1.3.0 instead of 2.0.0.