[EuiIcon] Create a filled version of the sparkles icon in EUI Borealis

[isaclfreire]

Problem Statement
When it comes to AI features, in 9.3 we are introducing a new gradient style for buttons and unfortunately the stroke-only version of the sparkles icon doesn't work as well on small surfaces as a filled version.

Proposed Solution
We would like to propose a filled version of the same design.

Urgency
Many different AI-related initiatives currently GA will be impacted by the change in 9.3.

Do alternatives or workarounds exist?
As a workaround we are currently using the stroke-only version, although it's not ideal.

Designs or Specs (Optional)
The filled icon can be found here. The gradient colors can be found here. I will create a branch in the EUI Figma library with the new icon request.

[MichaelMarcialis]

Commented in Slack, but adding here as well for visibility. Special exceptions for filled icons have been made for toggle-oriented icons and now important status icons. Unfortunately, I don't believe the sparkles icon meets the criteria for either. I would like to avoid making additional exceptions for filled icons to avoid creating more opportunities for inconsistency across our products. I think the choice between filled or stroked sparkles is purely subjective/aesthetic in this case and I think the stroked version looks completely fine in your examples.