Add id-for-municipality.R to the package, following R package standards

[CarwilB]

Incorporate id-for-municipality.R from the ultimate-consequences repository into the package.

This includes handling any files as new variables in data-raw/ by copying them from filepaths that begin with ../ultimate-consequences/. Code referencing the files and setting up variables needs to be moved to data-raw/municipality-tables.R.

dplyr and other library functions need to be in package::function form.