fix(ui5-list): focus list on non-focusable child click

[NakataCode]

Issue:

• The custom list item did not receive focus when its child elements (such as plain text or ui5-avatar) were clicked, as the child elements did not have their own focus state.

Solution:

• Added a focus check in fireItemPress to ensure the list item gains focus only if it doesn’t already have it.
• Updated the tabindex getter of the Avatar to use undefined instead of -1, and now when its not interactive we can focus the list when we click on the ui5-avatar.

Fixes: #10096

[PetyaMarkovaBogdanova]

It is ok, just in the second bullet point in Commit Message, you can specify the tab-index change is applied to the Avatar component.