add brcat alias + flag to decompress concatenated streams #594

Job	Run time
Build and test cmake:gcc9	29s
Build and test cmake:clang15	35s
Build and test cmake:clang15:asan	48s
Build and test cmake:clang15:tsan	46s
Build and test cmake:clang15:ubsan	51s
Build and test cmake:qemu-arm-neon-gcc	57s
Build and test cmake-osx:clang	1m 8s
Build and test cmake-osx:gcc	55s
Build and test cmake-win64:msvc-rel	44s
Build and test cmake-win64:msvc-dbg	46s
Build and test fuzz:clang15	34s
Build and test python3.10:clang15	1m 50s
Build and test python3.10-win	33s
Build and test maven	47s
Build and test bazel:root	34s
Build and test bazel:go	1m 2s
Build and test bazel:java	1m 55s
Build and test bazel:research	36s
Build and test bazel-osx:root	1m 31s
Build and test bazel-osx:go	1m 47s
Build and test bazel-osx:java	4m 26s
Build and test bazel-osx:research	1m 26s
Build and test bazel-win:root	1m 52s
Build and test bazel-win:java	4m 17s
Build and test bazel-win:research	1m 59s
	33m 8s

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