Add functionality to get zabbix map to grafana

[vryzhevsky]

Feature allows to get map json from zabbix in 3 manners:

1. Map properties
2. Map elements
3. Links

These data can be used to draw map in grafana or for other purposes.

[alexanderzobnin]

Sorry for delay - I'm still thinking about this and how better to include this without confusing users. Probably add feature toggle to the config page.

[vryzhevsky]

Sorry for delay - I'm still thinking about this and how better to include this without confusing users. Probably add feature toggle to the config page.

Do you have ideas how to merge this? I proposed this functianality as addidtinal types of requests like metrics, text, problems, etc... You can see this in code.

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[ivanahuckova]

Closing the PR as the Zabbix architecture has change too much since.