Format ThemePicker .kt files

1. kt-format existing .kt files with $ANDROID_BUILD_TOP/external/ktfmt/ktfmt.py <filepath>
2. Remove the exclusion of the files in ktfmt_includes.txt
Bug: 245751447
Test: Manual

Change-Id: Iad6e3ac101b59b521f535d72bdfe42a774bd7eaf