Apply tweaks for all users / default user

[Disassembler0]

This feature was often requested from the beginning (#5, #29 etc.), so it might be worth to look into it.

The basic idea would be to have a parameter (#241) to switch between single user and multiuser application. There are bunch of problems associated with that:

• Some tweaks target registry keys which don't exist in default account registry hive, and even if they are created, they will be ignored, deleted or rewritten on first login
• Multiuser application would require iterating over HKU subkeys where all the accounts are. There may be accounts for third party services, auxiliary accounts (e.g. nvidia drivers have one), domain accounts, roaming profiles etc. It's generally users' problem when something goes awry, but the script should be made safe enough not to cause total mayhem.
• If a single registry modification is to be applied several places (once for each user), then there needs to be some logic which makes it that way and will work only for HKCU:\. To make this work, the registry hive can be spoofed by remapping the PSDrive root to keep the tweak code clean, but there still needs to be some common/shared part which will do the looping.

Can you please add support in the #244 GUI (and using arguments for main script) to select target users? (like generic ones - CurrentUser, AllUsers (loop all valid users), DefaultUser (future users) and also specific ones listed on GUI runtime)