Simplify geometries (verticies) for generated task boundaries

[spwoodcock]

Describe the bug

• The geojson generated by the task splitting algorithm has too many vertices and are difficult to edit.
• Note: when editing a boundary, only a single geometry is edited at a time, so you have to move the boundary twice. Related issue Generate boundaries in splitting algorithm with Polygon Topology fmtm-splitter#24

To Reproduce

• Create a new project.
• On the task-splitting page generate the boundaries, then click the button to edit.

Expected behavior

• Geometries should be simplified on the fly by openlayers (test performance, it should be ok). There is the .simplify(tolerance) method on the Polygon class.
• It should preserve topology where it exists, i.e. preserve the boundaries.
• The goal is to reduce the number of vertices present, so that editing is easier.

Screenshots

Additional context
Add any other context about the problem here.

[spwoodcock]

Closing this in favour of hotosm/fmtm-splitter#24
Should be solved in the backend, not frontend (too complicated).
High priority task.