Add additional functions to pkggraph.go

[dmcilvaney]

Merge Checklist

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

• The toolchain has been rebuilt successfully (or no changes were made to it)
• The toolchain/worker package manifests are up-to-date
• Any updated packages successfully build (or no packages were changed)
• Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
• Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
• All package sources are available
• cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
• LICENSE-MAP files are up-to-date (./SPECS/LICENSES-AND-NOTICES/data/licenses.json, ./SPECS/LICENSES-AND-NOTICES/LICENSES-MAP.md, ./SPECS/LICENSES-AND-NOTICES/LICENSE-EXCEPTIONS.PHOTON)
• All source files have up-to-date hashes in the *.signatures.json files
• sudo make go-tidy-all and sudo make go-test-coverage pass
• Documentation has been updated to match any changes to the build system
• Ready to merge

---

Summary

In preparation for an implicit provides optimization PR (RFC/PoC: #6298), add a couple of functions to pkgraph:

• HasNode(): Returns true if a specific node object is present in a graph, the node must point to the same underlying object, equivalence is not sufficient.
• AllImplicitNodes(): Like the other All*Nodes(): returns a list of all run/remote nodes in the graph that have n.Implicit == true
• AddGoalNodeToNodes(): Creates a goal node that links to arbitrary node objects in the graph rather than package versions.

Change Log

• Add HasNode() AllImplicitNodes() AddGoalNodeToNodes()

Does this affect the toolchain?

NO

Test Methodology

• Local

[dmcilvaney]

Needs rebase on top of #5798 once merged