Illegal Characters Allowed In Extract Path

[CStarker]

The extract path cannot contain spaces per UnrealPak limitations but UnrealPakGUI allows the user to enter them. Other non-alphanumeric characters are likely disallowed but I haven't tested this. An invalid argument error and failed extract occurs if illegal characters are used. The error is not useful for discovering this limitation. UnrealPakGUI should prevent the user from entering illegal characters.