AncestorOrSelfDependencyNodeFilter uses identity equality and fails on cloned trees

## Summary
`AncestorOrSelfDependencyNodeFilter` matches nodes with `equals(...)`, but the node implementations do not override `equals`/`hashCode`, so the comparison is identity-based. The filter therefore only works when the candidate nodes are the exact same instances as the descendants, and silently matches nothing when applied to a rebuilt tree.

## Affected code
- `src/main/java/org/apache/maven/shared/dependency/graph/filter/AncestorOrSelfDependencyNodeFilter.java:82-92` — `isAncestorOrSelf(...)` compares with `ancestorNode.equals(descendantNode)`
- `src/main/java/org/apache/maven/shared/dependency/graph/internal/DefaultDependencyNode.java` — no `equals`/`hashCode` override

## Impact
`maven-dependency-plugin` combines this filter with `BuildingDependencyNodeVisitor` (which clones the tree). Because the clone produces different node instances, the ancestor-or-self matches never succeed and the filtered output is empty, even though the graph logically contains the nodes.

## Suggested fix
Implement value-based `equals`/`hashCode` on the node classes (e.g. by artifact coordinates), or compare by artifact in the filter instead of relying on node identity.

Start by reading AncestorOrSelfDependencyNodeFilter.java:82-92 and DefaultDependencyNode.java, then trace how BuildingDependencyNodeVisitor clones the tree. Reproduce the filter with rebuilt nodes and compare the result with the original-node case; done means ancestor-or-self matches work on the cloned tree and the filtered output is no longer empty.

Written by the indexing model from the issue text.