Adds a dropdown list of user's own topics in addition to search field.
Moves some hard-coded text into translation files.
Motivation and context
Generally users want to add their own topics to a learning path.
Screenshots
Checklist
[x] I have read and followed the CONTRIBUTING guide.
[x] 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.
Summary of changes
Motivation and context
Generally users want to add their own topics to a learning path.
Screenshots
Checklist