Test: Console output in a loop with short pauses in R

[DavisVaughan]

Issue: #4519
PR: #4848

Reprex:

tokens <- c(
  "",
  "Why",
  " do",
  " programmers",
  " prefer",
  " dark",
  " mode",
  "?\n\n",
  "Because",
  " light",
  " attracts",
  " bugs",
  "!"
)

for(token in tokens) {
  cat(token)
  Sys.sleep(0.01)
}

See the before/after videos for expected behavior:
#4848 (comment)

Mostly I'd like to get a test added to ensure that our Console isn't "dropping" any output in this particular case. The Sys.sleep(0.01) is important here!