Add `Help Request` menu to nav bar

[sergioacolis]

• [ ] There is a pull down menu on the Nav bar with the label Help Requests.
• [ ] When that label is clicked, we see a menu with a single open: List Help Requests.
• [ ] When the List Help Requests option is selected, the browser window goes to the route /helprequests/list
• [ ] Implement tests for Help Requests navbar