Installer: Add tests for manual license key set from CLI

Manual license keys can be set with offline installer using installer versions 4.2.x
1. Remove qtaccount.ini and qtlicenses.ini from disk
2. Try installing from CLI -> install should fail with errors
"Qt Account settings file [C:\\Users\\<username>\\AppData\\Roaming\\Qt\\qtaccount.ini] does not exist."
"No valid license keys found."
3. Install from CLI with --lk <license_key>,<license_key2> -> install success and qtlicenses.ini is written
4. Install from CLI without --lk -> install should success as it reads the qtlicenses.ini written in previous install
5. Install from CLI with --email <email> --pw <password> or with QT_INSTALLER_JWT_TOKEN env variable -> install success
6. Remove qtlicenses.ini and install from CLI without --lk and without --email -> install reads qtaccount.ini and logs in if internet connection found -> install success