Add multm_prev_ layer and enhance gemm() function for PLANE_WISE operations #1292

Job	Run time
ubuntu-latest-ffmpeg7	1m 19s
ubuntu-latest-clang-default-avx	29m 3s
ubuntu-20_04-gcc-7	26m 59s
ubuntu-latest-gcc-11-blas	26m 4s
ubuntu-latest-gcc-default-cmake-3-8-ffmpeg5	25m 2s
windows-2019	15m 25s
windows-latest	25m 25s
	2h 29m 17s

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