issue a clearer error message when queryRenderedFeatures parameters.layers isn't an Array

[andrewharvey]

Launch Checklist

• briefly describe the changes in this PR

if you call map.queryRenderedFeatures passing parameters.layers as a String such as layer by mistake (it expects an Array of strings) it will issue an error:

The layer 'l' does not exist in the map's style and cannot be queried for features.

This PR adds a different error message to let you know you need to pass an Array.

• write tests for all new functionality
• document any changes to public APIs

No changes.

• post benchmark scores
• manually test the debug page

[jfirebaugh]

Thanks!