GH-50014: [R] Replace imported symbol from bit64 (#50015)

I opted to delete the 'reexports' file because the symbols are not _actually_ re-exported. IMHO, it's more appropriate to just add this hook in arrow-package.R as done here, but of course if your strong preference is to retain the reexports-bit64.R file I'll restore it.

`integer64()` should be a fine choice -- I basically wanted a part of the API that has essentially 0 chance of ever changing.

As of today, `R CMD check` doesn't complain if you import a symbol and then don't reference it in the sources. Nor do I think such a check will ever happen.
* GitHub Issue: #50014

Lead-authored-by: Michael Chirico <michaelchirico4@gmail.com>
Co-authored-by: Michael Chirico <chiricom@google.com>
Signed-off-by: Jonathan Keane <jkeane@gmail.com>

Author: MichaelChirico

r/DESCRIPTION

@@ -147,7 +147,6 @@ Collate:
     'query-engine.R'
     'record-batch-reader.R'
     'record-batch-writer.R'
-    'reexports-bit64.R'
     'reexports-tidyselect.R'
     'schema.R'
     'udf.R'

r/NAMESPACE

@@ -427,8 +427,7 @@ export(write_tsv_dataset)
 importFrom(R6,R6Class)
 importFrom(assertthat,assert_that)
 importFrom(assertthat,is.string)
-importFrom(bit64,print.integer64)
-importFrom(bit64,str.integer64)
+importFrom(bit64,integer64)
 importFrom(glue,glue)
 importFrom(methods,as)
 importFrom(purrr,as_mapper)

r/R/arrow-package.R

@@ -30,6 +30,7 @@
 #' @importFrom rlang is_bare_list call_name
 #' @importFrom tidyselect vars_pull eval_select eval_rename
 #' @importFrom glue glue
+#' @importFrom bit64 integer64
 #' @useDynLib arrow, .registration = TRUE
 #' @keywords internal
 "_PACKAGE"