logical disk: Fix metrics for non drive letter disks

[jkroepke]

Fixes #1493
Fixes #1491

I introduce a dedicated windows_logical_disk_info metric here is avoid duplicate label info

# HELP windows_logical_disk_idle_seconds_total Seconds that the disk was idle (LogicalDisk.PercentIdleTime)
# TYPE windows_logical_disk_idle_seconds_total counter
windows_logical_disk_idle_seconds_total{volume="C:"} 3958.073043
windows_logical_disk_idle_seconds_total{volume="D:"} 3193.0903421
windows_logical_disk_idle_seconds_total{volume="D:\\Test"} 153.78342139999998
windows_logical_disk_idle_seconds_total{volume="HarddiskVolume2"} 2885.0179252
windows_logical_disk_idle_seconds_total{volume="HarddiskVolume3"} 2934.6000697
# HELP windows_logical_disk_info A metric with a constant '1' value labeled with logical disk information
# TYPE windows_logical_disk_info gauge
windows_logical_disk_info{disk="-1",filesystem="",partition="-1",serial_number="",volume="D:\\Test",volume_name=""} 1
windows_logical_disk_info{disk="-1",filesystem="",partition="-1",serial_number="",volume="HarddiskVolume2",volume_name=""} 1
windows_logical_disk_info{disk="-1",filesystem="",partition="-1",serial_number="",volume="HarddiskVolume3",volume_name=""} 1
windows_logical_disk_info{disk="0",filesystem="NTFS",partition="2",serial_number="668EEC37",volume="C:",volume_name="Windows"} 1
windows_logical_disk_info{disk="1",filesystem="NTFS",partition="0",serial_number="50AE953B",volume="D:",volume_name="Temporary Storage"} 1

[jkroepke]

In I switched from WMI to Win32 API.

This results into way more complicated code, but WMI (or the WMI go implementation) is terrible slow (up to 10 times).

WMI:

windows_exporter_collector_duration_seconds{collector="logical_disk"} 0.0153111

Win32 API:

windows_exporter_collector_duration_seconds{collector="logical_disk"} 0.0010479

[jacbo0112]

Looking forward to this

[jacbo0112]

I've been looking forward to this commit merging to master