standalone checks & assert n_max is a whole positive number

[JosiahParry]

Describe the bug n_max in arc_select() and arc_read() can be set to a negative number. This causes an error to be propagated with a confusing message. Instead, there should be an assertion like check_whole_number() to do this. arcgisutils has imported the standalone checks with proper rlang namespacing. These should be incorporated into arcgislayers to perform these checks