Restore original websocket commands for config entries

[marvin-w]

Proposed change

Partially rewrite #93387 (comment) to not have a breaking change in the WS API that currently breaks all custom panels using this and potentially also other custom frontend integrations.

Restore original websocket commands and add "config_entries/get_single"

See home-assistant/frontend#16647

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• I have followed the perfect PR recommendations
• The code has been formatted using Black (black --fast homeassistant tests)
• 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

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.
• Untested files have been added to .coveragerc.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[home-assistant]

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

Code owner commands

Code owners of config can trigger bot actions by commenting:

• @home-assistant close Closes the pull request.
• @home-assistant rename Awesome new title Renames the pull request.
• @home-assistant reopen Reopen the pull request.
• @home-assistant unassign config Removes the current integration label and assignees on the pull request, add the integration domain after the command.

[home-assistant]

Hey there @bdraco, mind taking a look at this pull request as it has been labeled with an integration (bluetooth) you are listed as a code owner for? Thanks!

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Code owners of bluetooth can trigger bot actions by commenting:

• @home-assistant close Closes the pull request.
• @home-assistant rename Awesome new title Renames the pull request.
• @home-assistant reopen Reopen the pull request.
• @home-assistant unassign bluetooth Removes the current integration label and assignees on the pull request, add the integration domain after the command.

[home-assistant]

Hey there @balloob, @bieniu, @thecode, @chemelli74, @bdraco, mind taking a look at this pull request as it has been labeled with an integration (shelly) you are listed as a code owner for? Thanks!

Code owner commands

Code owners of shelly can trigger bot actions by commenting:

• @home-assistant close Closes the pull request.
• @home-assistant rename Awesome new title Renames the pull request.
• @home-assistant reopen Reopen the pull request.
• @home-assistant unassign shelly Removes the current integration label and assignees on the pull request, add the integration domain after the command.

[emontnemery]

LGTM