Defguard client cannot cannot establish tunnel.

[Monkleys]

Describe the bug Defguard client cannot connect via defguard instance or imported config on Ubuntu 22.04.3 LTS

To Reproduce Steps to reproduce the behavior: Install and run:

1. Install defguard 0.2.0 or 0.2.1 from .deb with dpkg.
2. Run defguard from command line with defguard-client

Via instance:

1. Import instance with name and token
2. Select instance and connect to gateway
3. See "Unexpected error occurred"
4. Terminal logs:

   
   [2024-02-19][11:11:16][ERROR][k0@tauri://localhost/assets/index-241e4e48.js:68:7119] Invoking connect FAILED
   "IP address parse error: invalid socket address syntax"
   [2024-02-19][11:11:16][ERROR][k0@tauri://localhost/assets/index-241e4e48.js:68:7119] Error handling interface: IP address parse error: invalid socket address syntax

Via imported config
1. Click add tunnel
2. Select downloaded config and give it a name and click "Import Config file"
3. Select tunnel and click connect
4. See "Unexpected error occurred" 
5. Terminal logs:

[2024-02-19][11:13:10][ERROR][k0@tauri://localhost/assets/index-241e4e48.js:68:7119] Invoking connect FAILED "IP address parse error: invalid socket address syntax" [2024-02-19][11:13:10][ERROR][k0@tauri://localhost/assets/index-241e4e48.js:68:7119] Error handling interface: IP address parse error: invalid socket address syntax

**Expected behavior**
I expect the defguard tunnel to connect without an error thrown when tunnel is established.

**Version information**
- Defguard Core version: ghcr.io/defguard/defguard:latest
- Defguard Gateway version: ghcr.io/defguard/gateway:latest
 - Operating system and version running the gateway: Ubuntu 22.04.3 LTS

**Screenshots**

![def-guard](https://github.com/DefGuard/defguard/assets/22679921/b888a1e6-2d7f-407d-bcc2-7b13fe89ab99)

**Additional context**
Wireguard clients and configs have been used successfully, establishing a connection without the defguard client.

[teon]

The problem is:

• our one liner accepts VPN address as DNS - but our client doesn;t support DNS VPN server names.

I need to fix one-line installer

[teon]

The script now includes information that the VPN server should be as IP (not domain)