Title attribute for thumbnails in contents pane

[graykr]

As a user

I want to be able to view the full image titles for thumbnails in the contents pane by hovering over the image

So that viewing the full image titles from the contents pane is easier and more intuitive, thus allowing me to differentiate between the thumbnail images more readily

A related feature request was posted as an issue here: UniversalViewer/universalviewer#758

Currently only the first 8-9 characters of the image title are typically shown beneath the thumbnail. This is often not sufficient to differentiate between the images. Here are two examples:

https://universalviewer.io/uv.html?manifest=https://digital.library.illinois.edu/items/e2f4c960-5298-0138-7202-02d0d7bfd6e4-5/manifest

https://universalviewer.io/uv.html?manifest=https://digital.library.illinois.edu/items/893a0af0-9c97-0139-7888-02d0d7bfd6e4-2/manifest

In order to make it easier for users to differentiate between the images, I am proposing that a title attribute be added also to the thumbnail image so that the full title would display when a user hovers over the thumbnail. Right now this behavior is only occurring if the user hovers over the text of the partial title beneath the thumbnail.