find_package_root_file has uninformative error context

[JosiahParry]

I recently noticed that when rprojroot fails to find a file, the error that is shown is from normalizePath() and it doesn't show that it comes from find_package_root_file().

rprojroot::find_package_root_file("DESCRIPTION", path = "../definitelynot")
#> Error in `normalizePath()`:
#> ! path[1]="../definitelynot": No such file or directory

It would be very nice if there were an error_call = rlang::caller_call() argument here so that nicer error messages can be bubbled up. We use {rprojroot} extensively in {rextendr}.

[krlmlr]

So far, rprojroot is free of hard dependencies, I'd like to keep it that way. Would your proposed solution work if rlang and/or fs were only suggested?