WiX Toolset-Make the default install dir to "Program files"

Most of our program would be 64-bit, so the default install dir we expect to show to user is "C:\Program Files...", however it will be "C:\Program Files (x86)..." without some additional settings.

1. Change Id of Directory to 'ProgramFiles64Folder' from 'ProgramFilesFolder'

2. Go to the project solution file, change to <Platform Condition=" '$(Platform)' == '' ">x64</Platform>, then add <InstallerPlatform>x64</InstallerPlatform>

Reference: https://stackoverflow.com/questions/22932942/wix-heat-exe-win64-components-win64-yes/24396430#24396430