Feature/power scale changes for resiliency

[randeepdell]

Description

This PR enables resiliency for csi-powerscale driver.
Below are the changes.

common/constants/consts.go - added default values
common/constants/envvars.go - added env variable constants

helm/csi-isilon/values.yaml - specifies API port and arrayConnectivityPollRate
helm/csi-isilon/templates/controller.yaml - read the arrayConnectivityPollRate specified in podmon
helm/csi-isilon/templates/node.yaml - read the arrayConnectivityPollRate specified in podmon

As there is no Isilon platform support to test connecitivity, the below files poll the array from the k8s node and expose an API to test the connecitivity using probes.
service/controllerNodeToArrayConnectivity.go - forms the url and queries worker node for connecitity to array
service/nodeConnectivityChecker.go - periodically runs probe and returns the status when API is called.
service/service.go - starts the API connecitivity check

service/csi_extension_server.go - implements csi extension to enable podmon

service/isiService.go - calls API using gopowerscale lib to fetch active clients running IOs

GitHub Issues

dell/csm#262

GitHub Issue #

Checklist:

• I have performed a self-review of my own code to ensure there are no formatting, vetting, linting, or security issues
• I have verified that new and existing unit tests pass locally with my changes
• I have not allowed coverage numbers to degenerate
• I have maintained at least 90% code coverage
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Backward compatibility is not broken

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also list any relevant details for your test configuration

• Built the changes and tested the regular flow with podmon disabled.
• When podmon is enabled, able to see taint applied if k8s node goes down.
• When podmon is enabled, able to connectivity probe being run in logs.
• When podmon is enabled, able to check IOs being detected in logs.

[meggm]

Some checks are failing

[randeepdell]

Some checks are failing

Resolved.

[randeepdell]

Need reviewers to take a look at it.