Track Paths to exporters when troubleshoot PMM

User story:
As a PMM user, I need to have information about paths to running exporters in my diagnostics data

UI/UX:
`pmm-admin summary`

Acceptance criteria

• in addition to current information Summary and archive have information about paths to all exporters managed by pmm-agent

Out of scope:
TBD

Suggested implementation:
TBD

How to test:
TBD

Details:
We got a case when binaries for exporters updated in one location but Agent uses default paths so using old version of exporters

[[email protected] ~]# systemctl status pmm-agent.service
...
CGroup: /system.slice/pmm-agent.service
├─1374 /usr/sbin/pmm-agent --config-file=/usr/local/percona/pmm2/config/...
├─2466 /usr/local/percona/pmm2/exporters/node_exporter --collector.bondi...
└─2495 /usr/local/percona/pmm2/exporters/vmagent -envflag.enable=true