VPN-6399: Add Linux Qt build dependencies for accessibility

[oskirby]

Description

The smoking gun in the Qt build logs seems to be this:

Note: Disabling X11 Accessibility Bridge: D-Bus or AT-SPI is missing.

To enable X11 accesibility support, I think we just need to make sure that Qt is built with the development libraries libdbus-1-dev and libatspi2.0-dev installed.

Reference

JIRA Issue: VPN-6399

Checklist

• My code follows the style guidelines for this project
• I have not added any packages that contain high risk or unknown licenses (GPL, LGPL, MPL, etc. consult with DevOps if in question)
• I have performed a self review of my own code
• I have commented my code PARTICULARLY in hard to understand areas
• I have added thorough tests where needed

[bhearsum]

Do you want to add any checks to cmake or elsewhere to ensure this doesn't regress?

[mcleinman]

Thanks!