Add empty line after quarto comments

[vezwork]

Via @DavisVaughan in posit-dev/air#487:

Over in jolars/panache#115 we have been discussing an idea like this where the quarto comments are removed before styling, but when they are added back in an empty line should be added unconditionally between the quarto comments and the rest of the code block. That prevents cases like the above from looking so confusing. Can we make this change in Quarto? It seems like it would be an easy tweak.

So concretely:

---

If we start here

#| label: my label

## my R comment 1
a <- 1

## my R comment 2
b <- 2

Then we stay there.

---

If we start here

#| label: my label
## my R comment 1
a <- 1

## my R comment 2
b <- 2

then we add a line and end here

#| label: my label

## my R comment 1
a <- 1

## my R comment 2
b <- 2

---

if we start here

#| label: my label
a <- 1
b <- 2

we add a line and end here

#| label: my label

a <- 1
b <- 2

i.e. that empty line is unconditionally added to split the quarto directives from the rest of the code, even when there isnt a comment in the code itself

[vezwork]

A user reported in the Air R formatter repo that they feel that the lack of newlines after formatted quarto comments hinders readability. @mcanouil would you be interested to update the quarto comment formatting to always have a newline after the comments? I ask based on your recent work in: #655

[mcanouil]

Does it mean the cursor should also be moved one line below when quitting code cells options completion mode?

In my opinion, formatting is last resort. The tool should help getting it right in the first place.

[vezwork]

That makes sense to me to change in addition to changing the formatting!

[mcanouil]

I can take a look.

[vezwork]

cool :)