[FEAT] Directive to track when a sticky element gets pinned

[xelaint]

💡 Feature request

Feature Name

Directive to track when a sticky element gets pinned

The Desired Behavior

A directive (DaffStickyTracker) to calculate when a sticky elements gets pinned so it can add and remove a .is-pinned class to the element. This is so that we can change styles when it's sticky and when it's not.

i.e. when the footer buttons are sticky, there should be a top box shadow on the element. When it's no longer sticky and back as a relative element on the page, the box shadow should be removed.

Your Use Case

As a designer, I would like to be able to add and remove styles on sticky elements.

Prior Work

Environment

Daffodil version: X.Y.Z
Angular version: X.Y.Z 

 
For Tooling issues:
- Node version: XX  
- Platform:  

Others: