Broken links to stylesheet mean widgets won't display

Problem/Motivation

Social share widgets no longer display. If you look at the stylesheets the module references, they no longer exist. See https://sharecdn.social9.com/v2/css/os-share-widget-style.css -- sharecdn.social9.com no longer exists. (https://social9.com is still up, but that subdomain seems to have been eliminated.)

Steps to reproduce

Review a page with Open Social Share widgets enabled, e.g. https://dc.arcabc.ca/islandora/object/dc%3A40685

No widgets appear. Follow links to stylesheets being used; they are gone.

Proposed resolution

Package archived stylesheets with the module and refer to the local copies instead of the missing remote copies.

Remaining tasks

Obtain copies of the remote stylesheets, update code to refer to the local copy instead of the external link.