add support for nvenc and accel_assist #2357

Job	Run time
code formatting check	26s
cppcheck	5m 6s
min features with gcc	4m 22s
min features with g++	8m 37s
min features with clang	3m 20s
max features with gcc	9m 45s
max features with g++	5m 58s
max features with clang	7m 10s
max features with clang and AddressSanitized	5m 8s
max features with gcc and DEBUG	14m 0s
max features with gcc for 32-bit arch (legacy OS)	1m 44s
max features with g++ for 32-bit arch (legacy OS)	4m 17s
max features with clang for 32-bit arch (legacy OS)	3m 48s
	1h 13m 41s

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