Support semi colons on single line in statement range detection

[lionel-]

Branched from #636.
Addresses posit-dev/positron#4317

Adds a dependency of statement-range on the R parser. This is consistent with our plans to make evaluation of selections depend on the R parser as well (complete expressions detection).

When a statement range is requested, we simply check if the whole line completely parses. If that's the case we return the line range. This tactic doesn't work if multiline expressions are separated by semi-colons. We can find a better way when we switch to a Rowan implementation.

Positron Release Notes

New Features

• N/A

Bug Fixes

• Cmd/Ctrl + Enter now works as expected with expressions separated by semi-colons on a single line.
  Semi-colons not respected when running single line commands in R positron#4317

Positron QA Notes

Cmd/Ctrl + Enter on that line (or an empty preceding line) should run the entire line:

1; 2; 3

A semi-colon following a multiline expression is not supported yet, so for instance this would evaluate only the braces:

{
  1
}; 2