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

Hi,

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

*Issue :- *

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

*Solution:-*

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