added support for custom palettes

[bcpearce]

Proposed Changes

Add support for custom palettes.

Related Issues

https://github.com/frenck/python-wled/issues/1602

Summary by CodeRabbit

• New Features

  • Displays the count of custom palettes available on a WLED device.
  • Includes generated custom palette entries alongside standard palettes in listings.

• Bug Fixes

  • Ensures palette data is populated and represented consistently so both standard and custom palettes display correctly.

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