Enhance summarise to include row for country-level total, and columns for additional variables

[soniwe]

We also need a row for the total country-level coverage/percentage for each variable

We need to be able to handle variables with more than 2 levels e.g. vaccination (vacclevel) coded as "no vaccination", "incomplete vaccination", and "complete vaccination"? Also applies to missed opportunities variables "missottv", "missomcv", "missodptpol".

ADD columns for unweighted number children in each row (c_number_unw), weighted number of children in each row (c_number_w), and weighted proportion of children in each stratum (c_distribution).