add PV/PVC Namespace for PowerStore capacity metrics

[YianZong]

Description

add PV/PVC Namespace for PowerStore capacity metrics:

• powerstore_volume_logical_provisioned_megabytes
• powerstore_volume_logical_used_megabytes
• powerstore_filesystem_logical_provisioned_megabytes
• powerstore_filesystem_logical_used_megabytes

GitHub Issues

List the GitHub issues impacted by this PR:

GitHub Issue #
dell/csm#453

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 inspected the Grafana dashboards to verify the data is displayed properly
• 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
• I have maintained backward compatibility

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

• Test A
  UT:
  

• Test B
  Manual:
  
  
  
  

Manual inspection of the GUI

I have verified that the dashboards show the data properly while generating I/O and storage resources

• Yes
• No

[YianZong]

run e2e test

[YianZong]

run e2e test

[YianZong]

run e2e test