Improve Lovelace types

[piitaya]

Proposed change

Split lovelace types and utils into multiple files.

Introduce LovelaceRawConfig type to make a difference between raw configuration provided by the user and configuration to build the dashboard (this configuration can be computed using strategy). Same goes for LovelaceViewRawConfig type.
This change showed problems when casting a strategy dashboard to a cast devices. It's fixed with that PR too.
views property are no more required when using a strategy.

rawConfig is now required in the lovelace object. The default dashboard now injects a raw configuration (it was previously undefined) and configuration. The default dashboard is now handle as any strategy in term of configuration so it will be easier to add options for this default strategy or allow user to take control of any strategy.

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