Reorganize sockopts code and add several more socket options #3306

Job	Run time
Check nightly-only targets (nightly)	31s
Check selected Tier 3 platforms (nightly)	1m 46s
Check (stable)	4m 32s
Check --no-default-features (nightly)	1m 13s
Check (nightly)	4m 25s
Rustfmt	23s
Check (1.63)	4m 41s
Test rustix_use_experimental_asm (powerpc64le-linux)	1m 54s
Test (ubuntu)	1m 7s
Test use-libc (ubuntu)	1m 35s
Test (ubuntu-20.04)	1m 4s
Test use-libc (i686-linux)	1m 36s
Test (i686-linux)	1m 11s
Test use-libc (aarch64-linux)	3m 36s
Test (aarch64-linux)	1m 16s
Test use-libc (powerpc64le-linux)	1m 44s
Test (powerpc64le-linux)	1m 16s
Test use-libc (riscv64-linux)	1m 44s
Test (riscv64-linux)	1m 14s
Test use-libc (arm-linux)	1m 52s
Test (s390x-linux)	1m 13s
Test (arm-linux)	1m 15s
Test (ubuntu-stable)	1m 7s
Test (i686-linux-stable)	56s
Test (aarch64-linux-stable)	1m 17s
Test (riscv64-linux-stable)	1m 14s
Test (s390x-linux-stable)	1m 1s
Test (powerpc64le-linux-stable)	1m 11s
Test (arm-linux-stable)	1m 13s
Test (ubuntu-1.63)	1m 12s
Test (i686-linux-1.63)	1m 13s
Test (aarch64-linux-1.63)	1m 15s
Test (riscv64-linux-1.63)	1m 13s
Test (s390x-linux-1.63)	1m 12s
Test (powerpc64le-linux-1.63)	1m 13s
Test (arm-linux-1.63)	1m 14s
Test (macos-latest)	1m 11s
Test (macos-11)	5m 54s
Test (windows)	1m 1s
Test (windows-2019)	59s
	1h 6m 44s

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