manual resolver: delete GenerateAndRegisterManualResolver (#3960)
manual resolver: delete GenerateAndRegisterManualResolver (#3960)

Tests are using WithResolver dial option.
dfawley/grpc-go,stanley-cheung/grpc-go,dfawley/grpc-go,menghanl/grpc-go,grpc/grpc-go,menghanl/grpc-go,stanley-cheung/grpc-go,grpc/grpc-go