[feat] Convert Header to an Appbar

[mgcarpizo]

Feature Request

Summary

The current header occupies much of the page when it loads.
This would limit the number of featured devs shown on the page when it loads.

Solution

I suggest the use of an appbar that contains the logo, search bar, and buttons for devs and jobs.
It will also remain steady at the top even when a site visitor would scroll down to view other devs.