Add toggle switch for exposing of new entities to Assist

[jpbede]

Proposed change

Added a toggle switch to disable the exposure of new entities for Assist. As far as I saw core already supports this, but there was no possibility in the frontend so far.

WTH: https://community.home-assistant.io/t/wth-are-all-new-entities-exposed-to-assist-by-default/803889
This seems to be a feature request as well: https://community.home-assistant.io/t/assist-dont-expose-newly-added-entities-automatically-to-it/598434

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

[bramkragten]

Can we move the toggle row to below the assistants? Also can we make sure the toggle row text aligns with the assistant rows 😄

[jpbede]

Also can we make sure the toggle row text aligns with the assistant rows 😄

Dang it, why didn't I notice this before? 🙈
Should we align the assist rows with the rest?

[bramkragten]

Yeah, I think that is wise, the row was just copied from the alexa and google one right?

[jpbede]

Right