@turf/shortest-path Allow polygon feature as obstacle for shortestPath (#2941)

[ziegler-daniel]

Issue

This resolves #2941

Summary

• shortestPath accepts now a Feature<Polygon> obstacle as documented.

Checklist

• Meaningful title, including the name of the package being modified.
• Summary of the changes.
• Heads up if this is a breaking change.
• Any issues this resolves.
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[smallsaucepan]

Nice one. Thank you @ziegler-daniel