Handle route expansion on client

[lixmal]

Describe your changes

• Handle mgmt server handing out sources instead of single source
• Adds ipset to iptables and sets for nftables when len(sources) > 1
• Make refcounter more generic for that purpose

Issue ticket number and link

Checklist

• [x] Is it a bug fix
• [ ] Is a typo/documentation fix
• [x] Is a feature enhancement
• [x] It is a refactor
• [x] Created tests that fail without the change (if possible)
• [ ] Extended the README / documentation, if necessary

[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.8% Duplication on New Code

See analysis details on SonarCloud

[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.7% Duplication on New Code

See analysis details on SonarCloud

[pappz]

After I stop the agent the table ip netbird still exists. I tested with nft.