PR Submission checklist

GitHub Issues

List the GitHub issues impacted by this PR:

| GitHub Issue # |
https://github.com/dell/csm/issues/1961

Common PR Checklist:

• Have you made sure that the code compiles?
• Have you commented your code, particularly in hard-to-understand areas?
• Did you run tests in a real Kubernetes cluster?
• Have you maintained backward compatibility?
• Have you updated the mocks for any Client functions that have been modified (mocks/Client.go)?

Description of your changes:

Adding these changes more for consistency and to prevent accidental type conversions that might cause timeouts to go negative and cause context deadline issues. This also makes it easier for timeouts to be passed from driver efficiently. Inherently time.Duration does use int64 to represent time in nanoseconds.
This is first step as part of making timeouts configurable.
Why do we need this?
timeout can be specified as 10s, 2m, etc. the time.ParseDuration returns time in time.Duration instead of int64 and it makes it easier to take that value and pass it in the client in gopowerstore. When creating a new client, we used time.Duration(timeout)*time.Second. This would overflow when time.Duration is passed in via the driver as int64 representation of the time in nanoseconds (which is default). overflow would cause time to be negative.
Why was this not an issue in the past?
Timeouts were hardcoded and not read in dynamically.

Unit test:

coverage: 91.7% of statements
ok      github.com/dell/gopowerstore    1.080s  coverage: 91.7% of statements
coverage: 91.4% of statements
ok      github.com/dell/gopowerstore/api        31.395s coverage: 91.4% of statements