[pgAdmin4][runtime]: Fix #1310 - Application icon missing from runtime

Please find attached patch file for the fix of issue #1310.

Application icon is missing from runtime title bar when the exe is built on windows.

Qt5 :- 

Qt5 handle it automatically by adding RC_ICONS flag which contains the path of pgAdmin4.ico file to Qt project file.

Qt 4 :- 

We need to create pgAdmin4.rc file which contains pgAdmin4.ico file path to RC_FILE flag and we have to add this flag to Qt project file.

Do let us know for comments.

Thanks,

Neel Patel