Add AArch64-optimized SYMV kernels #5570

Job	Run time
build (ubuntu-latest, flang, make)	4m 44s
build (ubuntu-latest, gfortran, cmake)	44m 39s
msys2 (UCRT64, int32, None, mingw-w64-ucrt-x86_64, fc)	11m 57s
build (macos-latest, gfortran, make)	3m 16s
build (ubuntu-latest, flang, cmake)	9m 58s
build (ubuntu-latest, gfortran, make)	25m 1s
build (macos-latest, gfortran, cmake)	11m 50s
cross_build (riscv64, riscv64-linux-gnu, TARGET=RISCV64_GENERIC)	2m 39s
msys2 (UCRT64, int32, Release)	14m 27s
msys2 (CLANG64, int64, Release)	1h 11m 16s
cross_build (alpha, alpha-linux-gnu, TARGET=EV4)	2m 42s
neoverse_build	7m 22s
msys2 (CLANG64, int32, Release)	1h 12m 21s
cross_build (mipsel, mipsel-linux-gnu, TARGET=MIPS1004K)	3m 29s
cross_build (mips64el, mips64el-linux-gnuabi64, DYNAMIC_ARCH=1 TARGET=GENERIC)	3m 27s
msys2 (UCRT64, int64, Release)	13m 56s
msys2 (MINGW32, int32, Release)	15m 43s
	5h 18m 47s

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