Add/update port-based PWM class #58

Job	Run time
benchmark_apple-clang (g++, c++14)	2m 9s
benchmark_builds-avr (c++14)	22s
benchmark_builds-stm32f446 (c++14)	1m 42s
benchmark_apple-clang (g++, c++17)	2m 11s
benchmark_builds-stm32f446 (c++17)	2m 17s
benchmark_apple-clang (g++, c++20)	2m 39s
benchmark_single-cnl (g++, c++20)	14s
benchmark_builds-stm32f446 (c++2a)	2m 14s
benchmark_apple-clang (clang++, c++14)	2m 4s
benchmark_gcc-clang (g++, c++14)	1m 45s
benchmark_single-cnl (clang++, c++20)	13s
benchmark_apple-clang (clang++, c++17)	3m 10s
benchmark_gcc-clang (g++, c++17)	1m 42s
benchmark_apple-clang (clang++, c++20)	2m 15s
benchmark_gcc-clang (g++, c++20)	2m 1s
benchmark_single-stm32f429-qemu	57s
benchmark_single-stm32f429-qemu-cnl	49s
benchmark_gcc-clang (clang++, c++14)	1m 22s
benchmark_gcc-clang (clang++, c++17)	1m 32s
benchmark_single-stm32f446	55s
benchmark_gcc-clang (clang++, c++20)	1m 34s
	34m 7s

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