Add update integration

[ludeeus]

Breaking change

Proposed change

This adds a new update integration that allows other integrations to provide an updater platform to present and perform updates.
Similar to what we have for updates for supervisor (the hassio integration will migrate to this as well).

Type of change

• Dependency upgrade
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• New integration (thank you!)
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• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

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[probot-home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as it has been labeled with an integration (updater) you are listed as a code owner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[frenck]

I really dig this idea! Awesome!

However, I do think repurposing updater is causing it to have a weird name for a platform. I feel like the update platform is more consistent with our naming in general.

In the current schema of things, I would personally vote for removing the updater platform (as the use is gone), and introducing the update platform.

[ludeeus]

I'm fine with both

[balloob]

What if identifier or version is no longer valid ? We only validate domain. Would it help to drop domain_is_valid and just raise some exception if something is off?

[ludeeus]

Since we do not store updates anymore, that would mean that on each call info/update/skip we would need to gather all updates, then iterate over all updates for the domain to ensure the identifier and version are present.
That's expensive, and this I would say is a rare edge case, and if needed is something that the individual update platforms should handle, they get the identifier and version, and can raise or just return early if the update no longer exists.

[MartinHjelmare]

When will the arbitrary keyword arguments be used?

[ludeeus]

for backup and whatever we decide to add in the future.