QtIFW

Add the Predefined Variables in Component Scripting.

Add variables
 - ApplicationsDirX86
 - ApplicationsDirX64

Change that the application directory can be selected on Windows, don't depend on the architecture(32bit or 64bit) of QtIFW.

For example:
When on Windows(64bit version).
 - QtIFW(32bit version)
    - ApplicationsDir -> C:\Program Files (x86)
    - ApplicationsDirX86 -> C:\Program Files (x86)
    - ApplicationsDirX64 -> C:\Program Files
 - QtIFW(64bit version)
    - ApplicationsDir -> C:\Program Files
    - ApplicationsDirX86 -> C:\Program Files (x86)
    - ApplicationsDirX64 -> C:\Program Files

Change-Id: Idbc41d6f1ba9d7b0b9a9ff5590d05077662345cb
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Niels Weber <niels.weber@qt.io>
Reviewed-by: Katja Marttila <katja.marttila@theqtcompany.com>