Support new Token Authentication method for 7.x.x firmware

[gtdiehl]

Firmware 7.x.x requires a token to get retrieved from Enphase to be able to locally access the Envoy's web pages

This new functionality with gather a token either using the Commisioned or Uncommissioned option from Enphase's website. In addition to require a login credentials for the Enphase Enlighten website, when a user chooses the Commisioned option they will need to provide their Site ID and Serial Number as is shown in Enlighten. Only the login credentials are needed for the Uncommisioned option.

From tests there is also a slight time difference when these tokens from Enphase expire. Commisioned tokens expire after 12 hours and Uncommisioned token expire after 24 hours. In this library this will not be an issue as it only runs once, but when the library is used in an application such as Home Assistant that application code will need to take the expiration into account.

Pull request recommendations:

• [ ] Name your pull request your-development-type/short-description. Ex: feature/read-tiff-files
• [x] Link to any relevant issue in the PR description. Ex: Issue #78
• [x] Provide context of changes.
• [ ] Provide relevant tests for your feature or bug fix.
• [ ] Provide or update documentation for any feature added by your pull request.

Thanks for contributing!

[gtdiehl]

Code has been tested. Merging to release a Pre-Release build to be integrated into Home Assistant 2022.2.0.