Inclusion of Pediatrics age groups as optional Features

[azimov]

For running pediatrics based studies it is desirable to study specific age demographics.
This probably shouldn't be included by default, but it would be useful if these age demographics could be easily added to table 1 for any study, for example.

Note that this is not as simple as adding different age strata to the existing analysis as the age strata could be (for example) in the formats:

Standard format of age groups <1 years; 0 - <2 years; 2-5 years; 6-11 years; 12-17 years

Grouping used at https://datacenter.kidscount.org/ - 0-4; 5-11; 12-14; 15-17; 1-17; 3-17; 10-17

As well as others that may be of interest when comparing characterizations with other studies published in the literature.

In addition, it may be desirable to allow characterization for different categories of natal groups (i.e. ages in months) but I think this would be a different category not in any initial PR.

After doing this in a custom CohortDiagnostics study I feel this should be in FeatureExtraction as the community would benefit from adopting and allowing use of a standardized pediatrics covariates.