Add option to append extra string to user agent

[torredil]

Is this a bug fix or adding new feature?

New feature

What is this PR about? / Why do we need it?

Add an option to set a custom user agent.

It is recommended as a best practice to include a User-Agent header with every request. Doing this helps to more effectively diagnose and fix problems.

What testing is done?

Manual/CI/Unit Testing

[ConnorJC3]

Mostly good, but needs some fixes

Also, please change commit/PR name to something like "Add option to append extra string to user agent"

[ConnorJC3]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ConnorJC3

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[k8s-ci-robot]

@torredil: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-aws-ebs-csi-driver-test-e2e-external-eks-windows	339f2aa	link	false	/test pull-aws-ebs-csi-driver-test-e2e-external-eks-windows

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[ConnorJC3]

/retest