Add Agent (exporter) ports to pmm-admin output

• pmm-admin list
• pmm-admin status
• pmm-admin inventory list agents

Those commands should include ports used by exporters in their output – that's often required for debugging. For example, it would be easier to help https://forums.percona.com/discussion/56151/disable-node-exporter-or-limit-memory-used-by-it if ports were in the output.

UI/UX:

• pmm-admin list
• pmm-admin status
• pmm-admin inventory list agents

Acceptance criteria:

run commands written in UI/UX, user should to see ports of agents

How to test:

1. Run PMM server.

2. Run pmm-agent

3.  run commands written in UI/UX

4. check ports