Bug 1733329 - Update summary, developer name and description on Flathub r=mkaply DONTBUILD

GNOME Software 41 displays the developer_name very prominently on an
app's listing. Previously Firefox did not set one.

The summary should not repeat the app's name, but (quoting the spec)
should be "A short summary of what this component does".

Differential Revision: https://phabricator.services.mozilla.com/D126583

taskcluster/docker/firefox-flatpak/org.mozilla.firefox.appdata.xml.in

@@ -3,22 +3,12 @@
   <id type="desktop">org.mozilla.firefox</id>
   <launchable type="desktop-id">org.mozilla.firefox.desktop</launchable>
   <name>Firefox</name>
-  <summary>Mozilla Firefox Web Browser</summary>
+  <developer_name>Mozilla</developer_name>
+  <summary>Fast, Private &amp; Safe Web Browser</summary>
   <metadata_license>CC0-1.0</metadata_license>
   <project_license>MPL-2.0</project_license>
   <description>
-    <p>The Firefox standalone app for Linux is here</p>
-    <p>Get uncompromised access to the web by blending integrated privacy features and extensions with incredible performance.</p>
-    <p>Features:</p>
-    <ul>
-    <li>A powerful engine that’s built for rapidfire performance no matter how many tabs you’re switching between</li>
-    <li>Automatic privacy protection to safeguard your personal data against 2000+ online trackers</li>
-    <li>Faster page loading by blocking disruptive ads and scripts that hijack your browsing experience</li>
-    </ul>
-    <p>One account to sync them all</p>
-    <p>Seamlessly access passwords, bookmarks and more from all your devices. Plus, use the Send Tabs feature to instantly share open tabs between desktop, mobile and tablet.</p>
-    <p>Browse for good</p>
-    <p>We never track, collect or store your personal data. The Firefox Browser is made by Mozilla, the non-profit champions of a healthy internet. Mozilla also tackles issues like privacy, misinformation and trolling by investing in fellowships, campaigns and new technologies designed to make the internet a healthier place that’s open to everyone.</p>
+    <p>When it comes to your life online, you have a choice: accept the factory settings or put your privacy first. When you choose Firefox as your default browser, you’re choosing to protect your data while supporting an independent tech company. Firefox is also the only major browser backed by a non-profit fighting to give you more openness, transparency and control of your life online. Join hundreds of millions of people who choose to protect what's important by choosing Firefox - a web browser designed to be fast, easy to use, customizable and private.</p>
   </description>
   <releases>
 	<release version="$VERSION" date="$DATE"/>