Convert Hue to use unique ID

[balloob]

Breaking Change:

Hue will no longer import existing authentication from disk. It has not written this authentication to disk since March 2018.

Description:

Use Bridge ID consistently as a unique ID for config entries and config flows for Hue. Drops importing config from the old phue.conf files that we used to create prior to March 2018.

This further refines the unique_id work for config entries from #29806

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist

If the code does not interact with devices:

• Tests have been added to verify that the new code works.