Offsreen Rendering support based on Ozone EFL

Offsreen Rendering support based on Ozone EFL

Major changes:
1) Gets evas smart object created from ewk api and sets the same to
   GLSharedContextEfl to initialize evas gl context and surface.
2) Instantiates WindowTreeHost (Platform Window Delegate) in efl layer
   for adding webcontents native view as child of aura root window.
3) Initializes ScreenOzone in EwkGlobalData.
4) Adds runtime flag --enable-offscreen-rendering to enable offscreen flow.
5) Adds necessary command line flags to CommandLineEfl.
6) Fixes exit/shutdown crash while closing browsers (ewa/ubrowser).

Launch commands:
Desktop EFL : ./out.x64/efl_webview_app.sh
TM1 / TV    : /usr/apps/org.tizen.chromium-efl/bin/ubrowser

References:
1) [M94 Migration] Offscreen rendering with ozone-platform=efl
   https://review.tizen.org/gerrit/269556

2) Move ownership of aura::ScreenOzone to EwkGlobalData
   https://review.tizen.org/gerrit/277890

3) Avoid crash during cleanup and memory exceed
   https://review.tizen.org/gerrit/274512

Change-Id: I1ff270931af8e47011aca37e4f84e68e6d280db4
Signed-off-by: Gajendra N <gajendra.n@samsung.com>