Initial custom configuration for ZHA

[dmulcahey]

Proposed change

This PR adds support for custom configuration in ZHA. Initial support is added for setting a default transition time and for enabling / disabling the identity effect when devices are paired. Eventually this will be used for advanced network configuration as well.

REQUIRES home-assistant/core#48423 Merged

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