Change language for shape buttons' tooltips

[xmedr]

Overview

This changes the tooltip text in phase asset maps to use "select" and "selections" instead of "draw" and "layers".

Closes #259

Demo

Notes

This answer in a github issue on react-leaflet-draw was super useful in describing the structure of the leaflet.drawLocal attribute.

Testing Instructions

• Navigate or create a phase and go to its asset edit page
• Enter a search term to make assets appear
• Confirm that the tooltip to the right of the map uses language like
  • "Select using polygon" instead of "Draw a polygon"
  • "Clear selection" instead of "Clear layers"