ft: flextable (see 'flextable' package), table to shape into ECDC table layout
headers: dataframe including the multiple headers to add to the flextable object. Please note that the column col_keys should contain the names of the flextable object (i.e. col_key = names(x)), accordingly to set_header_df.
fsize: numeric, font to use (Default 7)
fname: character, font name (Default "Tahoma")
maincolor: character string, hexadecimal code for the header background color (Default EcdcColors(col_scale = "green", n=1))
lastbold: bolean, last row in bold (Default TRUE), usually used when the last row includes totals (EU/EEA totals)