Add r.session.levelOfObjectDetail=Normal for max.level=1

[renkun-ken]

What problem did you solve?

Closes #811

This PR

• Adds a new value Normal to setting r.session.levelOfObjectDetail corresponding to vsc.str.max.level=1 so that the task callback performance is much better in most cases.
• Adds a new setting r.session.objectTimeout to limit the cpu time of each capture.output(str(obj, max.level=)) call so that no single object takes too much time.

(If you do not have screenshot) How can I check this pull request?

Use the following example to check the performance in each case where r.session.levelOfObjectDetail is Minimal, Normal and Detailed.

n <- 10e4
ED <- lapply(1:20, function(i) {
  df <- lapply(1:60, function(j) rnorm(n))
  names(df) <- sprintf("x%d", seq_along(df))
  as.data.frame(df)
})

Both Minimal and Normal should have no notable performance issue, while Detailed would cause notable delay on user input.

[Fred-Wu]

How can I download this latest built?

[renkun-ken]

Download the artifact at https://github.com/REditorSupport/vscode-R/actions/runs/1327699240#artifacts which is at "Checks" -> "main push/pull request" -> artifacts.

[ElianHugh]

Sorry for the delay, been a bit swamped! I'll have a look over this now :)

[ElianHugh]

At first I didn't notice any difference between the three object detail settings, but I later realised this was because of the object timeout... Whoops! In that regard the fallback is pretty seamless!

As expected, minimal/normal settings do not occur a slowdown in comparison to detailed. Hover & str appear to be functioning as before.

LGTM! Thanks for the nice work!