GitHub Issue #1130: Metrics to track R & Python package usage

[cnathe]

Rationale

https://github.com/LabKey/internal-issues/issues/1130

The change instruments ExternalScriptEngine to record which R packages / Python modules scripts load, so the counts get reported to mothership via SimpleMetricsService. It does this by: (1) appending a language-specific "capture epilog" to the end of the user script that writes loaded packages to a sidecar file; (2) reading that sidecar back after the run and incrementing a per-package counter; and (3) adding a PythonScriptEngine subclass plus manager wiring to detect .py engines. All metric work is wrapped so it can never break script execution.

Related Pull Requests

Changes

• ExternalScriptEngine refactor to allow for getPackageCaptureEpilog, recordPackageUsage, and recordSuccessfulRun overrides
• RScriptEngine implementations for tracking package usages and recording via ScriptPackageUsageTracker.record()
• PythonScriptEngine implementations for tracking package usages and recording via ScriptPackageUsageTracker.record()
• ScriptPackageUsageTracker to use SimpleMetricsService to increment count of number of times a package was used

[cnathe]

@labkey-jeckels @labkey-matthewb note that this approach doesn't track anything for Jupyter reports or those that run via Rserve. Thoughts?