refactor: rename IMAMeasurementActive to IMAAnyMeasurementActive

[leodido]

Breaking rename that clarifies the IMA measurement probe semantics.

Breaking

Renamed FeatureIMAMeasurementActive → FeatureIMAAnyMeasurementActive, ProbeIMAMeasurementActive() → ProbeIMAAnyMeasurementActive(), and the SystemFeatures.IMAMeasurementActive field → IMAAnyMeasurementActive. The previous name implied the probe identified which func= rule was active; the new name clarifies it only detects that at least one IMA measurement has occurred. The CLI feature name changes from ima-measurement-active to ima-any-measurement-active. The String() output now includes the IMA any measurement active line in the Security Subsystems section.

Motivation

ProbeIMAMeasurementActive conflates "some IMA measurement happened" with "the specific measurement rule my caller needs is active." When runtime_measurements_count > 1, it returns Supported: true without identifying which func= rule caused the measurement. A caller needing func=BPRM_CHECK for exec hashing (to use bpf_ima_file_hash) could get a false positive if the measurements came from a different rule.

This rename is the first step toward a clearer API boundary. Follow-up PRs will add func-specific probes (ProbeIMAExecMeasurementActive, ProbeIMAFileCheckMeasurementActive) and a raw ReadIMARuntimeMeasurementsCount diagnostic helper.