[Web LA] Fix easing

[m-bert]

Summary

After #6163 was merged, each worklet function follows new naming convention. Since easings are worklets, their name property has also been changed. In web layout animations we were applying easing based on its name, therefore changing it resulted in only default linear easing being available on web.

This PR adds new Symbol into easing functions so that we can once again get their name and apply correct easing to animations.

Test plan

Tested on BasicLayoutAnimation example with Easing.exp

[tjzel]

This pattern is still far from perfect but 🚀