Ba/feature/add config setting for e84 logo

[bradleyandrick]

Related Issue(s):

• NA

Proposed Changes:

1. Add config var for SHOW_BRAND_LOGO
2. Update example config to include SHOW_BRAND_LOGO
3. Add new var info to readme
4. Update mock for tests
5. Fix prettier issue with new version (and add back in check for html)

To test

• edit local config.json file to include "SHOW_BRAND_LOGO": true
• run app
• confirm logo renders in top right of UI
• stop app
• change local config.json file to be "SHOW_BRAND_LOGO": false
• run app
• confirm logo does not render in top right of UI
• stop app
• change local config.json file to include a URL for DASHBOARD_BTN_URL like "DASHBOARD_BTN_URL": "https://www.google.com"
• run app
• confirm dashboard button renders correctly with and without brand logo showing

unit tests pass 🍏

PR Checklist:

• I have added my changes to the CHANGELOG or a CHANGELOG entry is not required.