feat(publicip): resilient public ip fetcher (#2518)

- `PUBLICIP_API` accepts a comma separated list of ip data sources, where the first one is the base default one, and sources after it are backup sources used if we are rate limited.
- `PUBLICIP_API` defaults to `ipinfo,ifconfigco,ip2location,cloudflare` such that it now has `ifconfigco,ip2location,cloudflare` as backup ip data sources.
- `PUBLICIP_API_TOKEN` accepts a comma separated list of ip data source tokens, each corresponding by position to the APIs listed in `PUBLICIP_API`.
- logs ip data source when logging public ip information
- assume a rate limiting error is for 30 days (no persistence)
- ready for future live settings updates
  - consider an ip data source no longer banned if the token changes
  - keeps track of ban times when updating the list of fetchers

internal/configuration/settings/settings_test.go

@@ -79,7 +79,11 @@ func Test_Settings_String(t *testing.T) {
 |   └── Process GID: 1000
 ├── Public IP settings:
 |   ├── IP file path: /tmp/gluetun/ip
-|   └── Public IP data API: ipinfo
+|   ├── Public IP data base API: ipinfo
+|   └── Public IP data backup APIs:
+|       ├── cloudflare
+|       ├── ifconfigco
+|       └── ip2location
 └── Version settings:
     └── Enabled: yes`,
 		},