write_permanent_sheets() writes and styles the Intro and Indicator List sheets
that are present in all cases taken into account by the different functions.
Arguments
- billion
Billion indicator names to return, either "hep", "hpop", "uhc" , or "all".
- start_col
integer start col of styling. Passed to
openxlsx::addStyle()- start_row
integer start row of styling. Passed to
openxlsx::addStyle()