Implement Coordinator for HEOS (initial plumbing)

[andrewsayre]

Proposed change

Starts the implementation of the coordinator for HEOS. This first step establishes the coordinator plumbing and moves the connection setup logic into the coordinator. Subsequent parts will move the logic of the 3 managers (ControllerManager, SourceManager, and GroupManager) into the coordinator.

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 is an incremental step from this larger PR that was closed: #135736

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
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• The code has been formatted using Ruff (ruff format homeassistant tests)
• Tests have been added to verify that the new code works.

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

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

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  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.
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[andrewsayre]

In the future, this (and the next try/except block) will have a specific message informing the user why setup failed. I can add that to this PR if that helps justify the repeated try/except blocks (I was trying to keep this PR as small as possible initially.)