Search persons by identifier

What does this mr do?

Closes issue #99 (closed) . Now you can add a person to an edition by typing (part of) the username, name, student number or the entire email of the person you want to add. The minimum length of the input for their identifier is 4 letters.

This will yield an overview of possible matches, along with their details and then you can add each individual person. You are required to assign a role to the person you want to add before proceeding.

Screenshots

Does this MR meet the acceptance criteria?

• I have added a changelog entry to reflect the significant changes I made.
• Tests were created to test the feature.
• I have updated the documentation accordingly.
• I adhere to the style guide.