Add support for update entity's update_percentage state attribute

[emontnemery]

Proposed change

Add support for update entity's update_percentage state attribute

Backend PR: home-assistant/core#128877

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:
• 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

[piitaya]

Do we need to have backward compatibility or not? Entities that are not migrated yet to the new format will not have percentage.
I'm ok with that but I wanted to be sure. Otherwise, the PR is ok for me.

[emontnemery]

@piitaya there's no need for backwards compatibility in frontend to my understanding, the linked core update integration PR makes sure that:

• Thein_progress state attribute is True if the update entity's in_progress property is True, or a number
• The update_percentage state attribute is a number if the update entity's in_progress property is a number, otherwise it's None / null

[bramkragten]

Will this attribute always be around, even when not updating or not supported?

[emontnemery]

Yes, that's how it's implemented in the core PR. If that's changed during the review of the core PR, this PR needs to be updated I think?

[bramkragten]

What is missing here is a change to the update screen in the voice assistant wizard, I'll add that tomorrow