Add more fonts to Rich Text editor

We currently provide only 3 very basic ones (serif, sans serif and monospace varieties). We could look into other Open Source options and maybe add them as options.

Start by locating the Rich Text editor implementation and its current serif, sans serif, and monospace font options. Identify suitable open-source fonts and confirm how they should be exposed as selectable options; the work is done when the additional approved fonts are available in the editor.

Written by the indexing model from the issue text.