docs: support opmetrics/pmetrics metric constructors in metrics doc generator

[DerekFrank]

Fixes #N/A

Description

The metrics documentation generator only recognized prometheus.New*() calls for extracting metric declarations from source code. After the migration to operatorpkg's opmetrics.NewPrometheus*() and pmetrics.NewPrometheus*() wrappers, the generator silently dropped all karpenter core and provider-aws metrics, producing incomplete documentation.

Changes:

• Use ast.Inspect to walk entire AST including function bodies, replacing the previous top-level-var-only scan. This picks up metrics initialized inside functions (e.g. node controller's initializeMetrics(), operatorpkg's RegisterClientMetrics()).
• Recognize opmetrics, pmetrics, and unqualified NewPrometheus* calls with the correct opts argument index (Args[1] instead of Args[0]).
• Skip unresolvable identifiers gracefully instead of fataling, since ast.Inspect encounters local variables in helper function bodies.
• Filter out _test.go files from parsing to avoid picking up test metrics.
• Add perObjectStatusMetrics() to generate the per-object status condition and termination metrics that are dynamically created at runtime by operatorpkg's status.NewControllerT.
• Add pmetrics.Namespace to the identifier mapping.
• Add per-object subsystem sort ordering and stability level entries.

How was this change tested?

Updated the docs as evidence of success

Does this change impact docs?

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

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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