Script fix for gui/lib/gui_resource.robot

Changes:
   - The open Browser keyword doesn't have the browser type
     argument like the Launch Headless Browser keyword.
   - Even passing the browser type argument in run time, the default
     browser is Firefox only launching.
   - Added Argument ${browser} in the Open Browser keyword inside
     Launch the Headless Browser keyword to launch the browser
     dynamically.

Tested:
    - No Test cases are involved with this keyword.
      We used this keyword for internal validation.

Change-Id: I10ee474694ed0dcbc6151a4a339d505a2eb09935
Signed-off-by: Yuvan Varshith A <[email protected]>

Author: yuvanvarshitha

gui/lib/gui_resource.robot

@@ -66,7 +66,7 @@ Launch Headless Browser
     #          (e.g. gc for google chrome, ff for firefox).
 
     Start Virtual Display
-    ${browser_ID}=  Open Browser  ${URL}
+    ${browser_ID}=  Open Browser  ${URL}    ${browser}
     Set Window Size  1920  1080
 
     RETURN  ${browser_ID}