Add the ability to toggle the reception of palette synchronizations

[felddy]

🗣 Description

This PR adds the ability to toggle the reception of palette synchronizations on a node.

• adds a new global receiveNotificationPalette
• adds a checkbox for "Palette" to the "Sync Setup" configuration page. (see screenshot)
• adds request handling of new form checkbox.
• adds logic to prevent the application of palette changes during synchronization.
• adds json serialization and deserialization of new configuration item.

Supported issues:

• Sync not working with colors only #2397

💭 Motivation and context

I want to keep the palette synchronized across all nodes, but need to preserve the effect on some of them.

🧪 Testing

Tested on four ESP32 nodes. Verified palettes can be synchronized without effects, and effects can be synchronized without palettes.

📷 Screenshots (if appropriate)

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
• Changes are limited to a single goal - eschew scope creep!
• All relevant type-of-change labels have been added.
• I have read the CONTRIBUTING document.
• These code changes follow [WLED code standards].

[blazoncek]

FYI palette, not pallet.
Otherwise looks ok to me.

[softhack007]

felddy force-pushed the feature/toggle_pallet_sync branch

@felddy please avoid force-pushing github while you have a PR open.
It has all kinds of subtle bad consequences, for example code review comments lost and bugreports being re-opened at random.

[felddy]

FYI palette, not pallet. Otherwise looks ok to me.

Doh! 🤦‍♂️
Spelling corrected, and image retested.
Fixed a palette typo in a comment in index.js as well.