Generate ThemePicker ktfmt inclusion file

The CL updates the ktfmt_includes.txt file used by
ThemePicker. Starting from this CL, all new Kotlin files will
be checked using ktfmt.

The ktfmt_includes.txt file is generated by the following steps:
$ cd $ANDROID_BUILD_TOP/packages/apps/ThemePicker
$ $ANDROID_BUILD_TOP/external/ktfmt/generate_includes_file.py --output=ktfmt_includes.txt src/ tests/ src_override/

Bug: 235461679
Test: Manual
Change-Id: I7d87d3a0a44b336d94f623b3e3db6fdcbb74b4b8