Support n-dimensional coordinates in scatter_points

[santisoler]

Description of the desired feature

Similarly to #138, verde.scatter_points assumes that region is [W, E, S, N], producing a random scatter set of points in 2D. Currently it only allows to add extra dimensions through the extra_coords argument, although they will have constant values.
Would be nice that verde.scatter_points allows a more general region and returns random n-dimensional coordinates.

For example:

import verde as vd

easting, northing, vertical = vd.scatter_points(
    region=[-100, 100, -100, 100, 10, 50], size=1000
)

This would be useful when working with harmonic functions, where each data point is given by three dimensional coordinates.

Are you willing to help implement and maintain this feature? Yes

[leouieda]

👍 thanks for opening this! It would be good to have this kind of support on all coordinate generation functions.