Add scripts to verify defect 3912

[ShobhitAd]

ATF Test Scripts to check #3912

This PR is ready for review.

ATF version

develop (smartdevicelink/sdl_atf@2645fc1)

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[jacobkeeler]

Seeing a lua panic on EXTERNAL_PROPRIETARY:

--- Preconditions -----------------------------------------------------------------------------------
kill: (1374783): No such process
[11:30:59,397] Clean_environment                                                                     [SUCCESS] (403 ms)
[11:31:00,835] Update_Preloaded_PT                                                                   [SUCCESS] (403 ms)
SDL pid 1374830
tcp        0      0 127.0.0.1:8087          0.0.0.0:*               LISTEN     
SDL started
HMI initialized
HMI is ready
Mobile #1 connected
SDL allowed
[11:31:03,406] Start_SDL__HMI__connect_Mobile__start_Session                                         [SUCCESS] (1970 ms)
[11:31:05,385] Register_App                                                                          [SUCCESS] (2823 ms)
--- Test --------------------------------------------------------------------------------------------
Lua panic: ...pts/Defects/8_2/3912_PTS_With_WSS_App_Content_Length.lua:71: attempt to index local 'httpRequest' (a nil value) (/home/jacobkeeler/sdl_atf/src/remote_adapter/remote_adapter_client/lua_remote_library.cc:16)
SCRIPT STATUS: ABORTED
'smartDeviceLinkCore' is running, PID: 1374830, terminating ...
Done

[ShobhitAd]

Seems that the HTTP header is only added to the binary data in PROPRIETARY mode https://github.com/smartdevicelink/sdl_core/blob/master/src/components/application_manager/rpc_plugins/sdl_rpc_plugin/src/commands/mobile/on_system_request_notification.cc#L127.

When the HTTP header is added by the sample_policy_manager for EXTERNAL_PROPRIETARY, it modifies the snapshot file directly https://github.com/smartdevicelink/sdl_core/blob/master/src/appMain/sample_policy_manager.py#L65. I've limited the test to PROPRIETARY policies