Add Bang & Olufsen button Event entities

[mj23000]

Proposed change

Add Event entities for the physical buttons on all Bang & Olufsen devices, except for the Beoconnect Core.

Supported buttons:

• Bluetooth
• Microphone
• Next
• Play / Pause
• Favourite 1
• Favourite 2
• Favourite 3
• Favourite 4
• Previous
• Volume

Each of these buttons have their own functions, but not all of them have functions on the different supported event types:

• Release of short press
• Long press
• Release of long press
• Very long press
• Release of very long press

For example, the Release of short press on the Bluetooth button is not used and can therefore be freely used for Home Assistant automations.

These Event entities are disabled by default.

Type of change

• [ ] Dependency upgrade
• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New integration (thank you!)
• [x] 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: https://github.com/home-assistant/home-assistant.io/pull/35062

Checklist

• [x] The code change is tested and works locally.
• [x] Local tests pass. Your PR cannot be merged unless tests pass
• [x] There is no commented out code in this PR.
• [x] I have followed the development checklist
• [x] I have followed the perfect PR recommendations
• [x] The code has been formatted using Ruff (ruff format homeassistant tests)
• [x] Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• [x] Documentation added/updated for www.home-assistant.io

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

• [x] 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.

To help with the load of incoming pull requests:

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