Reorganize sockopts code and add several more socket options (#855) #3313

Job	Run time
Rustfmt	9s
Check (stable)	10m 7s
Check (nightly)	9m 33s
Check --no-default-features (nightly)	1m 25s
Check selected Tier 3 platforms (nightly)	5m 23s
Check (1.63)	19m 29s
Check nightly-only targets (nightly)	33s
Test use-libc (ubuntu)	1m 31s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 32s
Test use-libc (i686-linux)	1m 46s
Test (ubuntu)	1m 17s
Test (ubuntu-20.04)	1m 19s
Test use-libc (aarch64-linux)	1m 37s
Test (i686-linux)	2m 5s
Test use-libc (powerpc64le-linux)	1m 55s
Test (aarch64-linux)	1m 30s
Test use-libc (riscv64-linux)	1m 32s
Test (powerpc64le-linux)	1m 32s
Test use-libc (arm-linux)	1m 24s
Test (riscv64-linux)	1m 33s
Test (s390x-linux)	1m 34s
Test (arm-linux)	1m 37s
Test (ubuntu-stable)	1m 8s
Test (i686-linux-stable)	1m 51s
Test (aarch64-linux-stable)	1m 45s
Test (riscv64-linux-stable)	1m 28s
Test (s390x-linux-stable)	1m 43s
Test (powerpc64le-linux-stable)	1m 30s
Test (arm-linux-stable)	1m 43s
Test (ubuntu-1.63)	4m 24s
Test (i686-linux-1.63)	4m 48s
Test (aarch64-linux-1.63)	4m 48s
Test (riscv64-linux-1.63)	4m 53s
Test (s390x-linux-1.63)	5m 45s
Test (powerpc64le-linux-1.63)	6m 43s
Test (arm-linux-1.63)	5m 36s
Test (macos-latest)	1m 14s
Test (macos-11)	1m 14s
Test (windows)	1m 14s
Test (windows-2019)	1m 50s
	2h 4m 0s

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