Add variance to the number of geometries/components in multipoint/multilinestring/multipolygon generator

[isVoid]

Description

This PR closes #1161

This PR adds normal distribution to the number of points, linestrings and polygons in the geometry generators. The generator API hasn't change, the parameters structs are now strongly typed with two different types: multipoint_normal_distribution_generator_parameter and multipoint_fixed_generator_parameter. The latter inherits the former because fixed output is a special case of normal distribution with stddev==0.

In the fixed generator case, the generator behave as it is today - every pair has exactly the same number of geometry per pair.

In the normal distribution generator case, each of the count parameter is treated as the mean of the distribution and sampled with a normal distribution, an additional stddev parameter is provided to control the variance. (Note that the count of geometry is always greater or equal to 1).

In this current draft PR, by setting num_point_per_multipoint=30, stddev=5, I can generate a multipoint_array with the number of point per multipoint with the following distribution:

stddev=0

stddev=20

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.