pfp: add constants to declare the compute method

PFP can be computed in different ways, filtering pods
which should or should not be included in the signature.
Two clear methods emerged yet:
- unrestricted/all: just include all pods known into the signature.
  This is probably the sane default for everyone.
- with-exclusive-resources: only include in the signature pods
  which have exclusive resources, because these are the pods which
  require NUMA/zone locality, everything else doesn't contribute
  to the NUMA accounting.

In this PR we add constants to express these two methods, this
way the entities which communicate through NRT objects have
a clear way to know how a PFP is computed.

Signed-off-by: Francesco Romani <[email protected]>

podfingerprint.go

@@ -51,6 +51,15 @@ const (
 	// Attribute is the recommended attribute name to use in
 	// NodeResourceTopology objects
 	Attribute = "nodeTopologyPodsFingerprint"
+	// AttributeMethod is the recommended attribute name to use
+	// in NodeResourceTopology objects to declare how the
+	// fingerprint was being computed
+	AttributeMethod = "nodeTopologyPodsFingerprintMethod"
+)
+
+const (
+	MethodAll                    = "all"                      // unrestricted. Just compute all the pods
+	MethodWithExclusiveResources = "with-exclusive-resources" // only consider pods which require exclusive resources
 )
 
 const (