Preparing for 2.2.0rc1

1. Add a version history
2. Update copyright years across the code base
3. Run format_all.sh
4. Update version strings from 2.1.0 to 2.2.0 in the docs and
   elsewhere.

Change-Id: I46d8d479d54bd6002d532785e67342106e73c9ac
diff --git a/package.xml b/package.xml
index 24dd29e..9d43e43 100644
--- a/package.xml
+++ b/package.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <!--
-  Copyright 2017 Google Inc. All rights reserved.
+  Copyright 2023 Google Inc. All rights reserved.
   http://ceres-solver.org/
 
   Redistribution and use in source and binary forms, with or without
@@ -30,7 +30,7 @@
 
 <package format="2">
   <name>ceres-solver</name>
-  <version>2.1.0</version>
+  <version>2.2.0</version>
   <description>A large scale non-linear optimization library.</description>
   <maintainer email="ceres-solver@googlegroups.com">
     The Ceres Solver Authors