Replace variable_collapse with `glue::collapse()`

[peterdesmet]

I found two cases:

frictionless-r/R/check_schema.R

Line 60 in 421c22f

field_names_collapse <- paste(field_names, collapse = "`, `")

frictionless-r/R/get_resource.R

Line 25 in 421c22f

resource_names_collapse <- paste(resource_names, collapse = "`, `")

Here's how to implement this better with glue

https://github.com/inbo/etn/blob/35e70f3d284cb64494313e667f238378564d494b/R/utils.R#L40-L43