@turf/shortest-path improve creation of point matrix for A* algorithm (#2943)

[ziegler-daniel]

Issue

This resolves #2943

Summary

• The creation of the point matrix for the A* algorithm has been improved.
• The distance between the points now corresponds to the specified resolution.
• I added additional test cases to check different resolutions.

Example

• Here is a visualization of the point matrix and shortest path for the start point, end point and obstacle from @turf/shortest-path produces inconsistent results for the same resolution in different units #2943 with {resolution: 20, units: 'meters'}: visualisation.json

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.
• Inclusion of your details in the contributors field of package.json - you've earned it! 👏
• Confirmation you've read the steps for preparing a pull request.

[smallsaucepan]

Thanks for putting this together @ziegler-daniel. Looks good. Have requested one minor change about the precision of the geojson used for the test cases.