add pure-kotlin decoder #656

Job	Run time
Build and test cmake:gcc9	46s
Build and test cmake:clang15	1m 0s
Build and test cmake:clang15:asan	45s
Build and test cmake:clang15:tsan	45s
Build and test cmake:clang15:ubsan	1m 7s
Build and test cmake:qemu-arm-neon-gcc	56s
Build and test cmake-osx:clang	50s
Build and test cmake-osx:gcc	1m 15s
Build and test cmake-win64:msvc-rel	1m 2s
Build and test cmake-win64:msvc-dbg	1m 1s
Build and test fuzz:clang15	28s
Build and test python3.10:clang15	1m 56s
Build and test python3.10-win	49s
Build and test maven	30s
Build and test bazel:root	28s
Build and test bazel:go	1m 0s
Build and test bazel:java	2m 20s
Build and test bazel:research	22s
Build and test bazel-osx:root	1m 2s
Build and test bazel-osx:go	3m 19s
Build and test bazel-osx:java	3m 51s
Build and test bazel-osx:research	1m 17s
Build and test bazel-win:root	1m 19s
Build and test bazel-win:java	8m 40s
Build and test bazel-win:research	1m 30s
	38m 18s

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