Automated install script & docker build for riscv64

### 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

I tried to run `curl -s -S -L https://raw.githubusercontent.com/AdguardTeam/AdGuardHome/master/scripts/install.sh | sh -s -- -v` on a riscv64 machine but the script complained `unsupported cpu type: riscv64`.

As far as I see, riscv64 is supported in #5704. I was indeed able to manually install it and everything works fine.

### Proposed solution

Please consider adding riscv64 to the automated install script:
https://github.com/AdguardTeam/AdGuardHome/blob/1d6d85cff4bf5915156f28d07582b4f0bb359d04/scripts/install.sh#L227

### Alternatives considered and additional information

_No response_