fix(ui5-icon): Icon now has a correct role

[vladitasev]

Until now ui5-icon had a fixed role attribute - it was always img.

Now, according to the accessibleName and interactive properties, it may be button, img or presentation.

The default role of all icons is now presentation. The only way to change this is to set either interactive to true (so you get role=button) or to set accessibleName, in which case you get img.

In addition: a missing closing </div> was added.

closes: #1581

[ilhan007]

I am approving the change from code point of you, up to you if you want to wait for the ACC expert input.