Apply Filter in "Warn" Mode

### 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

For users starting to use AdGuard or starting with a new-to-them ruleset, being able to apply a ruleset in "warn" mode could be a valuable tool. Users are often concerned that blocking too much will render applications crippled.

### Proposed solution

What is "warn" mode? AdGuard would not block the content but instead, log, highlight in yellow and allow the admin to review the impact of the applied rules.

### Alternatives considered and additional information

_No response_