[BUG] Lightning layer is not using settable distance units

[alanhargreaves]

Describe the Bug

Regardless of what the distance unit is set to (imperial or metric), src/plugins/layers/useLightning.js appears to only report in metric.

To Reproduce

Set distance units to imperial and view the lightning layer. It still reports in km.

Expected Behaviour

It should report in the units appropriate to the selected distance units.

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73!

[alanhargreaves]

/assign