Provide zones and endpoints (ex local) stats via /v1/status

[Al2Klimov]

No description provided.

[dnsmichi]

Windows builds are failing with

"C:\projects\icinga2\build\PACKAGE.vcxproj" (default target) (1) ->
"C:\projects\icinga2\build\ALL_BUILD.vcxproj" (default target) (3) ->
"C:\projects\icinga2\build\test\boosttest-test-base.vcxproj" (default target) (8) ->
"C:\projects\icinga2\build\lib\icinga\icinga.vcxproj" (default target) (10) ->
"C:\projects\icinga2\build\lib\remote\remote.vcxproj" (default target) (12) ->
(ClCompile target) -> 
  c:\projects\icinga2\lib\remote\statsreporter.cpp(45): error C2280: 'std::atomic_flag::atomic_flag(const std::atomic_flag &)': attempting to reference a deleted function [C:\projects\icinga2\build\lib\remote\remote.vcxproj]

[Al2Klimov]

$ curl .../v1/status/ClusterStats |python -mjson.tool

{
    "results": [
        {
            "name": "ClusterStats",
            "perfdata": [],
            "status": {
                "cluster": {
                    "node1": {
                        "endpoints": {
                            "node2": {
                                "connected": true,
                                "last_message_received": 1533213463.691841
                            }
                        },
                        "mtime": 1533213470.259481,
                        "uptime": 117.08613300323486,
                        "version": "v2.9.1-40-g30016a662"
                    },
                    "node2": {
                        "endpoints": {
                            "node1": {
                                "connected": true,
                                "last_message_received": 1533213453.690339
                            },
                            "node3": {
                                "connected": true,
                                "last_message_received": 1533213463.13135
                            }
                        },
                        "mtime": 1533213463.690132,
                        "uptime": 110.51873183250427,
                        "version": "v2.9.1-40-g30016a662"
                    },
                    "node3": {
                        "endpoints": {
                            "node2": {
                                "connected": true,
                                "last_message_received": 1533213453.69121
                            }
                        },
                        "mtime": 1533213463.129759,
                        "uptime": 110.31669497489929,
                        "version": "v2.9.1-40-g30016a662"
                    }
                }
            }
        }
    ]
}

[dnsmichi]

@lippserd this was considered for IcingaDB a while ago, needs a decision on proceeding.

[Al2Klimov]

@cla-bot check

[Al2Klimov]

Just trivially rebasing some PRs allowing to do so (regardless of their status!) to run GHA at all for the green checkmark. Please don't wonder. It's weekend after all soon, so no one gets blocked...