An ActionSet doesn't need to walk the graph.

Resolutions map back to the root, but actions do not. An iteration
works just fine.

Simplify TargetNodeSet so that it is directly iterable.

Bug: 261787132

Test: m droid dist compliance_dumpgraph compliance_dumpresolutions \
        compliance_sbom compliance_listshare compliance_rtrace \
        compliance_checkshare xmlnotice textnotice htmlnotice \
        compliancenotice_shippedlibs compliancenotice_bom

Test: m compliance_checkshare cts && \
        out/host/linux-x86/bin/compliance_checkshare out/host/linux-x86/gen/META/lic_intermediates/out/host/linux-x86/cts/android-cts.zip.meta_lic

Change-Id: Ic5a2d809b5a9a47b5d85f61e3a4a790dbe8f5fd2
diff --git a/tools/compliance/noticeindex.go b/tools/compliance/noticeindex.go
index dbfede6..c91a8df 100644
--- a/tools/compliance/noticeindex.go
+++ b/tools/compliance/noticeindex.go
@@ -42,7 +42,7 @@
 	// rs identifies the set of resolutions upon which the index is based.
 	rs ResolutionSet
 	// shipped identifies the set of target nodes shipped directly or as derivative works.
-	shipped *TargetNodeSet
+	shipped TargetNodeSet
 	// rootFS locates the root of the file system from which to read the files.
 	rootFS fs.FS
 	// hash maps license text filenames to content hashes