add brcat alias + flag to decompress concatenated streams #600

Job	Run time
Build and test cmake:gcc9	26s
Build and test cmake:clang15	34s
Build and test cmake:clang15:asan	40s
Build and test cmake:clang15:tsan	51s
Build and test cmake:clang15:ubsan	57s
Build and test cmake:qemu-arm-neon-gcc	1m 29s
Build and test cmake-osx:clang	43s
Build and test cmake-osx:gcc	57s
Build and test cmake-win64:msvc-rel	1m 22s
Build and test cmake-win64:msvc-dbg	1m 17s
Build and test fuzz:clang15	31s
Build and test python3.10:clang15	1m 46s
Build and test python3.10-win	44s
Build and test maven	34s
Build and test bazel:root	32s
Build and test bazel:go	1m 4s
Build and test bazel:java	1m 48s
Build and test bazel:research	51s
Build and test bazel-osx:root	1m 9s
Build and test bazel-osx:go	2m 26s
Build and test bazel-osx:java	3m 33s
Build and test bazel-osx:research	1m 22s
Build and test bazel-win:root	1m 35s
Build and test bazel-win:java	4m 9s
Build and test bazel-win:research	1m 42s
	33m 2s

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