add pure-kotlin decoder #657

Job	Run time
Build and test cmake:gcc9	30s
Build and test cmake:clang15	29s
Build and test cmake:clang15:asan	1m 26s
Build and test cmake:clang15:tsan	46s
Build and test cmake:clang15:ubsan	50s
Build and test cmake:qemu-arm-neon-gcc	57s
Build and test cmake-osx:clang	35s
Build and test cmake-osx:gcc	1m 8s
Build and test cmake-win64:msvc-rel	1m 2s
Build and test cmake-win64:msvc-dbg	1m 0s
Build and test fuzz:clang15	58s
Build and test python3.10:clang15	1m 43s
Build and test python3.10-win	1m 0s
Build and test maven	1m 29s
Build and test bazel:root	29s
Build and test bazel:go	1m 6s
Build and test bazel:java	2m 8s
Build and test bazel:research	1m 31s
Build and test bazel-osx:root	1m 35s
Build and test bazel-osx:go	2m 13s
Build and test bazel-osx:java	4m 40s
Build and test bazel-osx:research	1m 25s
Build and test bazel-win:root	1m 56s
Build and test bazel-win:java	4m 50s
Build and test bazel-win:research	1m 11s
	36m 57s

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