Use only the requested appdata folder, not the default one

[dbadol]

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If I launch the GUI wallet with an option defining a specific appdata folder to be used, it should only use that folder and not the default appdata path.

Example for a portable version of the Windows GUI Wallet, launched from a USB drive containing the Wallet app in folder "App" and the user data in folder "Data": start /B "" "%~dp0\App\Beam Wallet.exe" --appdata "%~dp0\Data"

Everything works fine with such a portable version, but a "cache" folder and a "QtWebEngine" folder are still crated in the default "%LOCALAPPDATA%\Beam Wallet" path. That should be avoided, so that no tracks are left on the computer after running such a portable version of the Wallet.