Update R syntax

[renkun-ken]

What problem did you solve?

Closes #646

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

1. Put cursor on any point of the following code and send code to terminal should send the whole pipeline to terminal.

1:10 |>
  sapply(\(x) x^2) |>
  sum()

[renkun-ken]

TBH I'm not quite familiar with the syntax file. Could you please point out if I don't do it right? @andycraig @Ikuyadeu

[Ikuyadeu]

OK, I'll check this weekend.
And, I'll try to make the test code for CI check.

[renkun-ken]

Should we do anything about the pipe-bind operator (=>) which is disabled by default unless environment variable _R_USE_PIPEBIND_ is set to a true value?

[ElianHugh]

Maybe for future proofing? Depends on whether the pipe bind operator is going to stay or not - this would lead me to believe it is, but then this twitter thread seems to go against that.

[Ikuyadeu]

@renkun-ken
OK, I checked the code. Thank you!
But testing CI is a bit hard now. So, I merge this once.

And, => should be let now, for confusing replacement. I think users should set that manually.
We can make voting if some users make a new issue about it.

[renkun-ken]

Do you encounter that most highlighting is lost with the latest release installed?

[renkun-ken]

Looks like https://github.com/Ikuyadeu/vscode-R/pull/647/files#diff-f6f05bbc187255f5cf06a39e3a4f7befa7288489c5fd44bb14586143076ffd1dR407-R447 is somehow problematic. I remove that code and the highlighting goes back to normal.