Create a prepare_upgrade.sh script to help for upgrades

This CL introduces a helper script to make it easier to upgrade ktfmt.
It creates maximum 2 CLs per repository already using ktfmt:
 - One that regenerates the ktfmt_includes.txt with the current version
   of ktfmt, so that all files already properly formatted are checked
   and files that are not already formatted are ignored. If the file is
   already up-to-date, then this CL won't be created.
 - One that reformats all files with the new version of ktfmt. This CL
   won't be created if all files are already formatted.

See http://ag/21117371 and http://ag/21117372 for an example of
generated CLs.

Bug: 266197805
Test: Ran the script and it worked!
Change-Id: I6e86c71ead20ec65512202ef2b2900b41f8feb2c

1 files changed, 6 insertions, 2 deletions

diff --git a/ktfmt.py b/ktfmt.py
index 3d337bb..7d93d36 100755
--- a/ktfmt.py
+++ b/ktfmt.py
@@ -39,6 +39,11 @@ def main():
       help='The file containing the Kotlin files and directories that should be included/excluded, generated using generate_includes_file.py.'
   )
   parser.add_argument(
+      '--jar',
+      default='',
+      help='The path to the ktfmt jar.'
+  )
+  parser.add_argument(
       'files',
       nargs='*',
       help='The files to format or check. If --include_file is specified, only the files at their intersection will be formatted/checked.'
@@ -91,8 +96,7 @@ def main():
   ktfmt_args += kt_files
 
   dir = os.path.normpath(os.path.dirname(__file__))
-  ktfmt_jar = os.path.join(
-      dir, '../../prebuilts/build-tools/common/framework/ktfmt.jar')
+  ktfmt_jar = args.jar if args.jar else os.path.join(dir, '../../prebuilts/build-tools/common/framework/ktfmt.jar')
 
   ktlint_env = os.environ.copy()
   ktlint_env['JAVA_CMD'] = 'java'