First implementation of physical_disk collector (#803)

* Added physical_disk collector.

Signed-off-by: Rob Scheepens <rob.scheepens@nutanix.com>
Signed-off-by: Brantley West <brantley@nutanix.com>

* exporter.go: Added physical_disk to defaultCollectors

Signed-off-by: Rob Scheepens <rob.scheepens@nutanix.com>
Signed-off-by: Brantley West <brantley@nutanix.com>

* Fix test cases for physicaldisk metrics

Signed-off-by: Rob Scheepens <rob.scheepens@nutanix.com>
Signed-off-by: Brantley West <brantley@nutanix.com>

* physical_disk.go: cleanup gofmt error

Signed-off-by: Brantley West <brantley@nutanix.com>

* physical_disk.go: populate physical disk 'number' label

Signed-off-by: Brantley West <brantley@nutanix.com>

* Added docs/collector.physical_disk.md.

Signed-off-by: Rob Scheepens <rob.scheepens@nutanix.com>

* physical_disk.go: change 'number' label to 'disk' to match node_exporter label

Signed-off-by: Brantley West <brantley@nutanix.com>

* physical_disk.go: adopt github.com/go-kit/log

Signed-off-by: Brantley West <brantley@nutanix.com>

* physical_disk.go: adopt include/exclude disk list

Signed-off-by: Brantley West <brantley@nutanix.com>

* fix: Add init config for physical_disk collector

Signed-off-by: Ben Reedy <breed808@breed808.com>

* chore: gofmt physical_disk collector

Signed-off-by: Ben Reedy <breed808@breed808.com>

---------

Signed-off-by: Rob Scheepens <rob.scheepens@nutanix.com>
Signed-off-by: Brantley West <brantley@nutanix.com>
Signed-off-by: Ben Reedy <breed808@breed808.com>
Co-authored-by: Brantley West <brantley@nutanix.com>
Co-authored-by: Ben Reedy <breed808@breed808.com>

Makefile

@@ -20,7 +20,7 @@ test:
 	go test -v ./...
 
 bench:
-	go test -v -bench='benchmark(cpu|logicaldisk|logon|memory|net|process|service|system|tcp|time)collector' ./...
+	go test -v -bench='benchmark(cpu|logicaldisk|physicaldisk|logon|memory|net|process|service|system|tcp|time)collector' ./...
 
 lint:
 	golangci-lint -c .golangci.yaml run