New-Skills: Add people search dropown

[Robin481]

Add back the people search dropdown that lists all the people on the skills application sorted by alphabet.

Change the root_url to /people and display the search there so we have back the starting point of the application.

Clicking on a name in the dropdown should redirect to the relevant profile but the search should still be there. Sort of a fixed header.

Orientate yourself on the old application for inspiration.

TODO:

• Re-Add the people search
• Make the root url /people, displaying the search bar
• Tests

[kcinay055679]

All Todos are done and implemented, but the featuretests on the github pipline are failing due to a unknown capybara error