Default exclude Headers, allow exclusions on all tags, and tooltips onclick

Problem/Motivation

We have the need for 3 additional features. I am in the process of creating a patch to post here with our solutions for these features so that we can use the patch and offer it to others if they are interested. The features are:

• Allow the default exclusion of headers from having a tooltip applied, if desired
• Allow the choice of glossify-exclude class to be applied to only span's or all tags
• Add ability to have a the tooltip work on-click rather that on hover, and provide a link in the tooltip to the content

Proposed resolution

Create an admin page for glossify at /admin/config/glossify that allows the user to choose whether to enable the above features.

User interface changes

Change the glossify-link.html.twig to allow for a popup onclick for the tooltip. Add supporting CSS/JS to provide the functionality needed to hide and popup the tooltip in the right location on the screen (preventing going off-screen when possible). Add the ability to show a link on the popup tooltip and its text.

Data model changes

Add "admin settings" which allow turning on/off the new features and for storing the link text. No actual data model added.