Favicon - Improve resolution for various display options

[mheppler]

When sharing a dataset or dataverse, the favicon file favicondataverse.png for the app tends to be used as the thumbnail to preview the page.

With it's 16 x 16 size, it is distorted and pixelated. There are tools like realfavicongenerator.net that can be used to generate the appropriate file types for various browsers and platforms.

[mheppler]

Managed to get an improved icon displayed when sharing (80px is the magic number for Slack, see attached). Still hope to revise and improve upon this. Slowly learning about the og:image meta tag, and it's best practices. Work here is going to input feedback for #5641. Might back out some of the changes here, before submitting a pull request, in order to move them over that issue as feedback for @qqmyers on his PR.