add pure-kotlin decoder #644

Job	Run time
Build and test cmake:gcc9	29s
Build and test cmake:clang15	31s
Build and test cmake:clang15:asan	46s
Build and test cmake:clang15:tsan	1m 6s
Build and test cmake:clang15:ubsan	51s
Build and test cmake:qemu-arm-neon-gcc	1m 15s
Build and test cmake-osx:clang	1m 6s
Build and test cmake-osx:gcc	55s
Build and test cmake-win64:msvc-rel	43s
Build and test cmake-win64:msvc-dbg	38s
Build and test fuzz:clang15	26s
Build and test python3.10:clang15	1m 47s
Build and test python3.10-win	42s
Build and test maven	38s
Build and test bazel:root	34s
Build and test bazel:go	1m 10s
Build and test bazel:java	45s
Build and test bazel:research	41s
Build and test bazel-osx:root	1m 50s
Build and test bazel-osx:go	2m 46s
Build and test bazel-osx:java	2m 32s
Build and test bazel-osx:research	1m 9s
Build and test bazel-win:root	1m 19s
Build and test bazel-win:java	3m 21s
Build and test bazel-win:research	1m 18s
	29m 18s

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