Rework focus and blur event handlers

[jonandernovella]

The event handlers now use a arrow fn so that the fns do not fire everytime a component rerenders. Also, now only one row may be selected at a time.

Related issue(s) and PR(s)

This PR closes #523

Type of change

• Bug fix (non-breaking change which fixes an issue)

List of changes made

• Event handlers are passed via props using arrow funcs
• We call the correct fn upon ESC when closing the comment area

Testing

• Usual procedure

Definition of Done checklist

• I have made an effort making the commit history understandable
• I have performed a self-review of my own code and commented any hard-to-understand areas
• Tests and lint/format validations are passing
• My changes generate no new warnings

[HenrikeW]

Nice, works!