refactor(ui5-shellbar): introducing assistant slot

[plamenivanov91]

Тhe showCoPilot property and the co-pilot-click event of the ui5-shellbar have been removed.
In their place we now have a public slot called assistant. We recommend using ui5-toggle-button with sap-icon://da and sap-icon://da-2 icons (see the examples below).

BREAKING CHANGE:

1. The showCoPilot property of the ui5-shellbar is removed.

If you have previously used the showCoPilot property:

<ui5-shellbar show-co-pilot></ui5-shellbar>

it will no longer work for the component.

2. The CoPilotAnimation feature of the ui5-shellbar is removed.

If you have previously used the CoPilotAnimation feature:

import CoPilotAnimation from "@ui5/webcomponents-fiori/dist/features/CoPilotAnimation.js"

it will no longer work for the component.

3. The copilotDomRef getter of the ui5-shellbar is removed.

If you have previously used the copilotDomRef public getter:

shellbar.copilotDomRef

it will no longer work for the component.

4. The co-pilot-click event of the ui5-shellbar is removed.
   If you have previously used the co-pilot-click public event:

shellbar.addEventListener("ui5-co-pilot-click", function(event) {
	...
});

it will no longer work for the component.

You can achieve similar functionality with the new slot:

HTML:

<ui5-shellbar>
  <ui5-toggle-button id="assistant" icon="sap-icon://da" slot="assistant"></ui5-toggle-button>
</ui5-shellbar>

JavaScript:

assistant.addEventListener("click", function (event) {
	const toggleButton = event.target;
	toggleButton.icon = toggleButton.pressed ? "sap-icon://da-2" : "sap-icon://da";
});

Related to #8461, #7887

[nnaydenow]

Remove all the generated css files from:

packages/fiori/test/pages/resources/css/
packages/main/test/pages/resources/css/