Collapse long learning objective/pre-requisite fields when viewing a learning path

[fbacall]

Summary of changes

• Add expandable option to display_attribute, which limits the max vertical height of the attribute value, adding a "See more/less" link to expand/collapse.
• Makes expandable elements expand to max height when "See more" is clicked, instead of gradually showing more content.
• Add some spacing between icons and text in user menu.

Motivation and context

#1096

Screenshots

Checklist

• I have read and followed the CONTRIBUTING guide.
• I confirm that I have the authority necessary to make this contribution on behalf of its copyright owner and agree
  to license it to the TeSS codebase under the
  BSD license.

[smza]

@fbacall is it possible to have Learning Objectives of each module under the module itself?