PoC: AI Button Animation

[NHristov-sap]

This is a copy of another PR #10242 , but this time animations should be done with keyframes.

[NHristov-sap]

It seems that animations don't

[NHristov-sap]

It seems that keyframes animations don't work in Chrome/Edge because of Chrome bug - if the @keyframes definitions are located in the CSS files of the components to which exported parts belong - everything works fine in Chrome/Edge, but if these definitions are in the main CSS (of the AI Button) - animations work only in Firefox. For example:

@keyframes fadeOutText {...} should stay in <ui5-ai-button> CSS
@keyframes fadeOutIcon {...}, @keyframes fadeOutEndIcon {...} should stay in <ui5-button> CSS
@keyframes fadeOutArrowButton {...} should stay in <ui5-split-button> CSS

then all works fine, otherwise if all of these are in <ui5-ai-button> CSS, animations work only in Firefox.