Animate color changes on node text

[s9ferech]

Summary

When entering or leaving profiling mode (implemented in PR enso-org/ide#1546), the text on nodes changes between a neutral color and colorful syntax highlighting. This change should be animated, but we currently do it instantly, from one frame to another, because every change to the text color is very expensive due to issue #2622.

Value

The transition will look smooth and will be in sync with other elements.

Specification

Every change to a node's text color should be animated smoothly using ensogl::data::color::Animation.

Acceptance Criteria & Test Cases