Formatting sends wrong response when line endings are supposed to be changed

[farwyler]

When line endings are changed during a formatting request, the whole document is sent to the client.

rust-analyzer/crates/rust-analyzer/src/handlers.rs

Lines 1874 to 1884 in 65874df

	let (new_text, new_line_endings) = LineEndings::normalize(captured_stdout);
	if line_index.endings != new_line_endings {
	// If line endings are different, send the entire file.
	// Diffing would not work here, as the line endings might be the only
	// difference.
	Ok(Some(to_proto::text_edit_vec(
	&line_index,
	TextEdit::replace(TextRange::up_to(TextSize::of(&*file)), new_text),
	)))
	} else if *file == new_text {

The change is correctly detected and new_text contains the changed endings.
But then to_proto::text_edit_vec subsequently changes the line endings back, because it uses the ones passed in by line_index instead of new_line_endings

So the actual TextEdit in the response contains new_text with the old line endings.

Steps to reproduce

1. be on LF system
2. open file with CRLF endings
3. make document formating request

4. rust-analyzer/crates/rust-analyzer/src/handlers.rs

   Line 1876 in 65874df

   if line_index.endings != new_line_endings {

   reports CRLF -> LF change and new_text contains LF endings
5. the client receives TextEdit replacing the document but still containing CRLF endings

This results in clients receiving the whole document on each request, because they always make requests with line endings that rust-analyzer wants to convert.