[FER] Extend Custom Upstream DNS Configuration in Client Settings

### 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

Currently, the custom upstream DNS configuration within the client settings in AdGuard Home is relatively basic and lacks the advanced options available in the global DNS settings. This limitation restricts flexibility and use cases.

### Proposed solution

I propose enhancing the client-side custom upstream DNS configuration to provide feature parity with the global DNS configuration, specifically including:

1. DNS Query Mode Selection
- Support for Load Balancing (round-robin)
- Support for Parallel Queries (concurrent requests, fastest response used)
- Support for Fastest IP mode
2. Bootstrap DNS Server Configuration
- Ability to specify dedicated bootstrap DNS servers for resolving upstream DNS hostnames, to improve privacy and resolution accuracy
3. DNS Service Settings
- Support for rate limiting (bandwidth or query rate limits)
- Support for whitelisting (allowing access from specified clients or IP ranges to the upstream DNS service)
4. DNS Cache Configuration
- Detailed cache management options (cache size, TTL control, cache eviction policies, etc.)

#### Expected Benefits
- Enable a single AdGuard Home instance to run multiple DNS services with different upstream DNS strategies per client
- Enhance flexibility and efficiency in DNS querying for faster and more reliable resolution
- Provide finer control for increased security and privacy
- Support more complex network environments and advanced use cases such as customized routing or split DNS
#### References
- Current advanced upstream DNS options available in the global DNS settings UI

### Alternatives considered and additional information

_No response_