add pure-kotlin decoder #646

Job	Run time
Build and test cmake:gcc9	33s
Build and test cmake:clang15	34s
Build and test cmake:clang15:asan	58s
Build and test cmake:clang15:tsan	46s
Build and test cmake:clang15:ubsan	52s
Build and test cmake:qemu-arm-neon-gcc	1m 0s
Build and test cmake-osx:clang	35s
Build and test cmake-osx:gcc	46s
Build and test cmake-win64:msvc-rel	42s
Build and test cmake-win64:msvc-dbg	57s
Build and test fuzz:clang15	48s
Build and test python3.10:clang15	1m 36s
Build and test python3.10-win	1m 0s
Build and test maven	34s
Build and test bazel:root	33s
Build and test bazel:go	1m 7s
Build and test bazel:java	1m 18s
Build and test bazel:research	26s
Build and test bazel-osx:root	1m 16s
Build and test bazel-osx:go	2m 37s
Build and test bazel-osx:java	2m 13s
Build and test bazel-osx:research	1m 1s
Build and test bazel-win:root	1m 2s
Build and test bazel-win:java	3m 35s
Build and test bazel-win:research	1m 11s
	28m 0s

Provide feedback