MB 39: Add home page about:mullvad-browser

browser/app/profile/000-mullvad-browser.js

browser/base/content/browser-places.js

browser/base/content/browser.js

browser/base/content/utilityOverlay.js

browser/components/BrowserGlue.sys.mjs

browser/components/about/AboutRedirector.cpp

browser/components/about/components.conf

browser/components/moz.build

...mponents/mullvad-browser/AboutMullvadBrowserChild.sys.mjs

...ponents/mullvad-browser/AboutMullvadBrowserParent.sys.mjs

browser/components/mullvad-browser/content/2728-sparkles.svg

...omponents/mullvad-browser/content/aboutMullvadBrowser.css

...components/mullvad-browser/content/aboutMullvadBrowser.js

...ponents/mullvad-browser/content/aboutMullvadBrowser.xhtml

...components/mullvad-browser/content/mullvadBrowserFont.css

browser/components/mullvad-browser/jar.mn

browser/components/mullvad-browser/moz.build

browser/components/newtab/AboutNewTabService.jsm

browser/components/preferences/home.inc.xhtml

browser/components/preferences/preferences.xhtml