Add a demo HTTP Transport option to the hello_world example #262

Job	Run time
build_attest_all (buildconfigs/key_xor_test_app.sh)	4m 59s
build_attest_all (buildconfigs/oak_client_android_app.sh)	25m 3s
build_attest_all (buildconfigs/oak_containers_agent.sh)	5m 38s
build_attest_all (buildconfigs/oak_containers_kernel.sh)	4m 11s
build_attest_all (buildconfigs/oak_containers_orchestrator.sh)	7m 48s
build_attest_all (buildconfigs/oak_containers_stage1.sh)	6m 8s
build_attest_all (buildconfigs/oak_containers_syslogd.sh)	7m 40s
build_attest_all (buildconfigs/oak_containers_system_image.sh)	15m 22s
build_attest_all (buildconfigs/oak_containers_nvidia_system_image.sh)	16m 22s
build_attest_all (buildconfigs/oak_echo_enclave_app.sh)	4m 56s
build_attest_all (buildconfigs/oak_echo_raw_enclave_app.sh)	4m 0s
build_attest_all (buildconfigs/oak_functions_enclave_app.sh)	4m 19s
build_attest_all (buildconfigs/oak_functions_insecure_enclave_app.sh)	4m 33s
build_attest_all (buildconfigs/oak_orchestrator.sh)	5m 14s
build_attest_all (buildconfigs/oak_restricted_kernel_simple_io_init_rd_wrapper_bin.sh)	5m 9s
build_attest_all (buildconfigs/stage0_bin.sh)	5m 9s
	2h 6m 31s

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