[Bug] New IconTasklist favorite icon not themable

[JoshStrobl]

Description

With the inclusion of the rewritten IconTasklist in #553, the favorite icon was changed to a new heart (budgie-app-favorited / budgie-app-unfavorited). This icon has a fixed color (Budgie's green) rather than any primary color defined by the theme.

@EbonJaeger and I both independently investigated making this effectively a symbolic that would be themed using .alert class that our existing notification icon uses, however the theming does not apply correctly to the popover.

This should be investigated and resolved (either with a proper fix or a revert to old iconography) before our next release.

Budgie version

git-bf436dbf53963a18209b6c10bb738f56db899580

Operating System

Fedora 40

Steps to reproduce the issue

Right click on an IconButton, notice that the favorited icon (if the app is favorited) is a fixed green.

Actual result

Icon not themable.

Expected result

Icon is themable.

Additional information

No response