feat: add option for extra hourly cost per host

[jasonwbarnett]

Fixes #5163

Description

This feature allows specifying an extra hourly cost per host for thing like Datadog APM agent, etc.

How was this change tested?

1. Create a nodepool with only xlarge and 2xlarge instance sizes.
2. Created a test Deployment with 1 pod with 1 cpu/2GB memory requests with 100 replicas.
3. Modify the nodepool and add all instance sizes.
4. Modify the karpenter-aws-provider deployment and set EXTRA_HOURLY_COST_PER_HOST to "1.0"

Does this change impact docs?

• Yes, PR includes docs updates
• Yes, issue opened: #
• No

Other Info

I considered adding the extra hourly cost per host to the static pricing for environments without access to the pricing API. However, this would require passing context into Reset() based on the current implementation, which introduces significant ripple effects across the entire test stack. I’m curious if anyone has alternative ideas or solutions to address this challenge.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

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[jasonwbarnett]

I just submitted this PR and wanted to reach out for help and guidance. If I missed anything or there are changes you’d like me to make, please let me know—I’m more than happy to address them promptly. Thanks for taking the time to review this!