Feature: Support check_multi output for performance data

[LordHepipud]

We should update the PerfData write for Icinga for Windows to output performance data as check_multi output, allowing easier integration within graphing solutions.

This is dynamically not really parseable by solutions:

Invoke-IcingaCheckProcess -Process msedge
[OK] Process Overview: 1 Ok
| 'msedge_process_count'=42c;; 'msedge_page_file_usage'=5424752B;;;0;9728 'msedge_cpu_usage'=0%;;;0;100 'msedge_thread_count'=802c;; 'msedge_memory_usage'=4178043000B;;;0;68636310000

A better approach would be, to use check_multi format for this:

Invoke-IcingaCheckProcess -Process msedge
[OK] Process Overview: 1 Ok
| 'msedge::CheckProcess::process_count'=42c;; 'msedge::CheckProcess::page_file_usage'=5424752B;;;0;9728 'msedge::CheckProcess::cpu_usage'=0%;;;0;100 'msedge::CheckProcess::thread_count'=802c;; 'msedge::CheckProcess::memory_usage'=4178043000B;;;0;68636310000

By doing so, we can select the current process for example, choose the CheckProcess template and receive the proper label for displaying graphs.

We do however require some sort of flag to ensure users can switch between the current PerfData writer and the new version.