[Feature Request] Client Settings : add Whitelist / Unblock to

### Prerequisites

- [X] I have checked the [Wiki](https://github.com/AdguardTeam/AdGuardHome/wiki) and [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions) and found no answer

- [X] I have searched other issues and found no duplicates

- [X] I want to request a feature or enhancement and not ask a question

### The problem

Today, to use the Global blocking features (large list of domains we can turn on/off) with some clients Unblocking for those same domains we must do a lot of work by either using...
1/ custom filters for each separate client
2/ create a new/separate Block List for each separate client (under Client Setting)

### Proposed solution

Proposing a carbon copy of the current 'Client / Block Specific Services' with a page that is 'Unblock Specific Services' (aka Whitelist)... where this page is the final check. It would also be "smart" and automatically remove any duplicate that is marked as blocked under 'Client / Block Specific Services' page.

This helps greatly when the Global Block Settings you want for the majority of clients but you have several clients you do not want many of those domains blocked. Its a lot of work to add all the custom filters for each client to unblock, or to redo the client specific blocklist.

### Alternatives considered and additional information

no other easy way to do this, all current ways are a lot of work.