Update Avatar docs samples to use tooltips

[rolfsmeds]

What is the problem?

In V22, Avatars got title based tooltips automatically based on their name: https://vaadin.com/docs/v22/ds/components/avatar.

In V23 and V24, the title attribute was replaced with a tooltip slot for the new tooltip feature, but no tooltip seems to be automatically generated: https://vaadin.com/docs/v23/components/avatar

(For some reason the AvatarGroup samples do have automatic tooltips, but not the standalone Avatars)

Related: the name should probably be also reflected as aria-label to be on the safe side #1614

Browsers

• Chrome
• Firefox
• Safari
• Safari on iOS
• Edge

Screen Readers

• None
• NVDA
• JAWS
• VoiceOver on MacOS
• VoiceOver on iOS

[web-padawan]

Actually, in V23 we changed to make tooltips opt-in via withTooltip property. We should still fix #1614 though.

[rolfsmeds]

Right, then we'll have to update documentation accordingly.