feat: add the pixelArea supercharged

[12rambau]

Supercharge the pixelArea vanilla method to allow computation in defined units.

import ee, LDCGEETools

hectares = ee.Image.pixelArea("ha").rename("ha")
acres = ee.Image.pixelArea("acres").rename("acres")
total = hectares.addBands(acres)

buffer = ee.Geometry.Point(0,0).buffer(100)
values = total.reduceRegion(ee.Reducer.mean(), buffer, 1)
values.getInfo()