Convert dhcp watcher to asyncio

[bdraco]

#110059 should merge fix since it will conflict here

Proposed change

Convert dhcp watcher to asyncio.

This is the last discovery method to be converted to async which means no more threads for any built-in discovery methods.

https://github.com/bdraco/aiodhcpwatcher. This uses a similar implementation to what we have but does non-blocking I/O and has coverage for a few more cases and dhcp server quirks (idna vs utf-8 encoding of hostnames)

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 Ruff (ruff format 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.

[bdraco]

All seems to work great on Mac and Linux

Will make aiodhcpwatcher

[bdraco]

tests pass on mac, need to fix them on linux

[bdraco]

Thanks. Really nice to get the integration down to low 400 lines