fix: add details to UnknownError

[therustmonk]

Description

This PR adds (requires) details to UnknownError.

Motivation and Context

Related to #3423
Without the fix some errors are indiscernible. Example:

     Running `target/debug/tari_base_node`
Initializing logging according to "/home/denis/.tari/config/log4rs_base_node.yml"
10:47 ERROR Network discovery errored: Connectivity error:
    Internal actor response was unexpectedly cancelled. Waiting for 5s
10:47 ERROR DhtConnectivity exited with error: ConnectivityError(ActorDisconnected)
UnknownError
10:47 ERROR Exiting with code (102): UnknownError

With the fix:

     Running `target/debug/tari_base_node`
Initializing logging according to "/home/denis/.tari/config/log4rs_base_node.yml"
10:48 ERROR Network discovery errored: Connectivity error:
    Internal actor response was unexpectedly cancelled. Waiting for 5s
UnknownError("Failed to initialize tor hidden service: TorClientError: Command failed:
    Authentication failed: Wrong length on authentication cookie.")
10:48 ERROR Exiting with code (102): UnknownError("Failed to initialize tor
    hidden service: TorClientError: Command failed: Authentication failed:
    Wrong length on authentication cookie.")

How Has This Been Tested?

Manually by activating CookieAuthentication 1 option in the Tor's settings.

[SWvheerden]

LGTM