Feature request: Support for WireGuard Host as a URL (FritzBox Configuration Incompatibility)

[EyyupA]

What's the feature 🧐

Description:
When using the FritzBox WireGuard configuration with Gluetun, it fails to connect because the WireGuard host is specified as a URL (e.g., myfritzaddress.myfritz.net) instead of an IP address.

Currently, Gluetun attempts to parse the host value into an integer, which causes an error when a URL is provided. This issue makes it impossible to use dynamic DNS addresses like the ones provided by FritzBox (MyFritz).

Steps to Reproduce:
1. Configure Gluetun with a WireGuard configuration file exported from a FritzBox router.
2. Use a dynamic DNS address (e.g., myfritzaddress.myfritz.net) as the WireGuard host.
3. Start Gluetun and observe the failure due to the host being parsed incorrectly.

Expected Behavior:
Gluetun should support URLs as valid WireGuard hosts and resolve them correctly to an IP address.

Proposed Solution:
Update the parsing logic for the WireGuard host to support both IP addresses and URLs, resolving the latter to an IP address dynamically.

Extra information and references

Wireguard config:

[Interface]
PrivateKey = 
Address = 192.168.11.201/22,fd10:ed98:ee8f::201/64
DNS = 192.168.8.1,fd10:ed98:ee8f::d624:ddff:fe73:27f8
DNS = fritz.box

[Peer]
PublicKey = 
PresharedKey = 
AllowedIPs = 192.168.8.0/22,0.0.0.0/0,fd10:ed98:ee8f::/64,::/0
Endpoint = abcdefghijklmnop.myfritz.net:12345
PersistentKeepalive = 25

[github-actions]

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