fix(arborist): link meta-only optional peers in linked strategy

[manzoorwanijk]

In continuation of our exploration of using install-strategy=linked in the Gutenberg monorepo, which powers the WordPress Block Editor.

Under install-strategy=linked, an optional peer dependency declared only in peerDependenciesMeta (with no matching entry in peerDependencies) was not linked into the dependent's isolated node_modules, even when an ancestor in the graph provided it.
For example @emotion/react declares react in peerDependencies and @types/react only in peerDependenciesMeta; after a linked install its store node_modules contained react but not @types/react, so its shipped .d.ts could not resolve the React typings under strict isolation and the breakage cascaded into consumers as TypeScript errors.

The root cause is that npm only creates dependency edges from peerDependencies.
A peer named only in peerDependenciesMeta gets no edge at all.
The isolated reifier materializes a dependency into a package's store node_modules only when the package has a resolved edge for it (edge.to.target), so the meta-only optional peer was silently dropped.
Required peers (and optional peers that also appear in peerDependencies) have edges and were materialized correctly; meta-only optional peers were the gap.

This PR resolves the gap in #assignCommonProperties in isolated-reifier.js.
After the edge-derived dependency lists are built, it iterates peerDependenciesMeta, and for each optional entry that is not already a dependency it resolves the name against the tree via node.resolve() and, when found, materializes it as an optional store dependency.
Because the peer is added to the package's store dependency set, the store instance's hash is keyed by it, and it resolves to the same instance the consumer uses rather than a duplicate copy.
If no ancestor provides the peer, node.resolve() returns nothing and it stays omitted, preserving optional semantics.

References

Fixes #9460

[github-actions]

🎉 Backport to release/v11 created: #9485