Add Armv7M support for Cortex-M4 and Cortex-M7 #595

Job	Run time
examples_basic	1m 44s
examples_ntt_kyber_dilithium_neon_core	11m 52s
examples_ntt_kyber_dilithium_helium_core	3m 35s
Dry Run (slothy.targets.arm_v7m.cortex_m4)	1m 38s
fft	7m 17s
Dry Run (slothy.targets.arm_v7m.cortex_m7)	33m 33s
sqmag	1m 40s
Dry Run (slothy.targets.arm_v81m.cortex_m55r1)	3m 4s
Dry Run (slothy.targets.arm_v81m.cortex_m85r1)	2m 32s
tutorial	6m 30s
Dry Run (slothy.targets.aarch64.cortex_a55)	8m 1s
Dry Run (slothy.targets.aarch64.cortex_a72_frontend)	33m 49s
Dry Run (slothy.targets.aarch64.apple_m1_firestorm_experimental)	25m 51s
Dry Run (slothy.targets.aarch64.apple_m1_icestorm_experimental)	24m 0s
	2h 45m 6s

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