Migrate gl-text-blue-600 -> ???

"See epic for example migrations using Tailwind classes and apply rules using background, text, and icon design tokens.

Ignore any styles within syntax highlighting themes, these do not require migration to design tokens as they are the same regardless of color mode and will be resolved in &15846 (closed).

Any complex or specific usage of colors can be delegated to newly created seperate issues under the same MR to help make reviews simpler, for example, framework styles like dropdown etc.

Ensure that colors are applied appripriatly to elements, for example text.color.heading is used on <hx> elements, icon.color values are used on <gl-icon> using the variant prop."