Allow using private keys and certificate chains from Traefik's acme.json file instead of specifying private key/certificate-chain string/path to file.

### 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

Good day,
I am using Traefik's ACME service and would like to use certificates retrieved by Traefik. Traefik stores them in a json file, and i would like AdGuardHome to read the json file for certificates.
Would it be possible?
Thank you!

### Proposed solution

Configure a setting to read Traefik's acme.json file.

### Alternatives considered and additional information

Using community written scripts, but complicated to maintain automation of converting json to pem files.