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/internal/ceres/generate_bundle_adjustment_tests.py b/internal/ceres/generate_bundle_adjustment_tests.py
index 35865a6..bed96d1 100644
--- a/internal/ceres/generate_bundle_adjustment_tests.py
+++ b/internal/ceres/generate_bundle_adjustment_tests.py
@@ -1,5 +1,5 @@
 # Ceres Solver - A fast non-linear least squares minimizer
-# Copyright 2018 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
@@ -93,7 +93,7 @@
 
 COPYRIGHT_HEADER = (
 """// Ceres Solver - A fast non-linear least squares minimizer
-// Copyright 2022 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