Add energy compare with previous year

[karwosts]

Proposed change

Add a toggle between comparing previous period and previous year.

I considered many different ways to approach this, e.g. if there should be another date picker, multiple preset options, compare with year-2 or year-3, etc, but eventually just decided to start with the most simple/limited possible implementation to get started. Am happy to do this a different way if we prefer a different UI. But from what comments I saw comparing with the previous year seemed to come up the most often as a request.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

Additional information

• This PR fixes or closes issue: fixes #

• This PR is related to issue or discussion:
  https://community.home-assistant.io/t/wth-why-can-i-only-compare-periods-in-the-energy-dashboard-with-the-previous-period/467189
  https://community.home-assistant.io/t/wth-energy-dashboard-comparison-make-compare-date-selectable/802790

• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

[Madelena]

Hello @karwosts , I am working on a design for the calendar picker for comparison use. Would love to talk to you more about it over here or Discord.

[karwosts]

Sure I'm happy to chat about it. Either here or maybe in the frontend project channel?

Flexibility of a calendar picker would be nice, though I'm a bit hesitant to introduce more usage of our current calendar given that it is not accessible, and several users have complained that they cannot use it. So I would feel bad to proliferate it further 😢

[boern99]

Will this feature be implemented? It would be very valuable for me and certainly for others as well.

[bramkragten]

Sure I'm happy to chat about it. Either here or maybe in the frontend project channel?

Flexibility of a calendar picker would be nice, though I'm a bit hesitant to introduce more usage of our current calendar given that it is not accessible, and several users have complained that they cannot use it. So I would feel bad to proliferate it further 😢

Would something like https://github.com/WickyNilliams/cally (demo: https://wicky.nillia.ms/cally/) fix that?