Use values in relationship To/From fields (#2871)

* use pkg values in relationship fields

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* add linter rule for using values in relationships

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* use new cmptest package for comparing relationships

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* create cmptest for common cmp.Diff options in test

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* condense matches for relationship ruleguard

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* remove relationship type from rules

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* restore build tag

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* suggest using values

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

* nil check pkgs

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

---------

Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>

internal/cmptest/relationship.go

@@ -0,0 +1,26 @@
+package cmptest
+
+import (
+	"github.com/sanity-io/litter"
+
+	"github.com/anchore/syft/syft/artifact"
+)
+
+type RelationshipComparer func(x, y artifact.Relationship) bool
+
+var relationshipStringer = litter.Options{
+	Compact:           true,
+	StripPackageNames: false,
+	HidePrivateFields: true, // we want to ignore package IDs
+	HideZeroValues:    true,
+	StrictGo:          true,
+	//FieldExclusions: ...  // these can be added for future values that need to be ignored
+	//FieldFilter: ...
+}
+
+func DefaultRelationshipComparer(x, y artifact.Relationship) bool {
+	// we just need a stable sort, the ordering does not need to be sensible
+	xStr := relationshipStringer.Sdump(x)
+	yStr := relationshipStringer.Sdump(y)
+	return xStr < yStr
+}