Add Metric for License Expiry

[neevnuv]

Please confirm the following

• I agree to follow this project's code of conduct.
• I have checked the current issues for duplicates.
• I understand that AWX is open source software provided for free and that I might not receive a timely response.

Feature type

New Feature

Feature Summary

Add a metric to show the time until the license for the awx/automation controller will expire.

Select the relevant components

• UI
• API
• Docs
• Collection
• CLI
• Other

Steps to reproduce

Currently the license expiry date is save as a label in the awx_system_info metric

Current results

Cannot query prometheus on license expiry easily in promql

Sugested feature result

Being able to monitor with prometheus alerts when the awx license is expiring (mostly relevent for AnsibleAutomationPlatform)

Additional information

I opened a PR for this feature request - #15483