fix(Dashboard): Sync color configuration via dedicated endpoint

[geido]

SUMMARY

This PR introduces a new endpoint which purpose is to store color configurations for a dashboard. Dashboard color configurations might need syncing and persistence in the backend even when the user takes no action. For instance, new data might appear on the dashboard that needs to be synced with the color maps and persisted. Previously, these changes would be saved using the dashboard PUT endpoint, causing that the dashboard last modified date would show up as updated even though no change was made from the user perspective, causing confusion. Also, issues have surfaced where metadata that wasn't meant to be persisted yet would go along with the updated color metadata, causing unexpected behaviors.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N.A.

TESTING INSTRUCTIONS

1. Open a Dashboard
2. Make sure new data appeared (new dimensions or metrics)
3. Observe how a network request is made to store the color metadata when leaving the dashboard
4. Make sure the last modified date of the Dashboard hasn't changed

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[Antonio-RiveroMartnez]

lgmt after addressing the comments