Move intent registration to own integration

[balloob]

Breaking Change

If you use the built-in intents for shopping list, cover or light, you need to add intent: to your configuration.yaml.

Description:

This moves the integration intent registration that is currently done in async_setup by Shopping List, Cover and Light to be the responsibility of the Intent integration.

I am thinking that we should consider this pattern also for other things where integrations inter-relate. Like the frontend panels.

The idea is that it will open up the door to add more intents to all integrations without loading it when not needed.

CC @synesthesiam

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist

If the code does not interact with devices:

• Tests have been added to verify that the new code works.

[probot-home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as its been labeled with a integration (cover) you are listed as a codeowner for? Thanks!

[probot-home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as its been labeled with a integration (intent) you are listed as a codeowner for? Thanks!

[probot-home-assistant]

Hey there @home-assistant/core, mind taking a look at this pull request as its been labeled with a integration (conversation) you are listed as a codeowner for? Thanks!