Send correct line endings to language servers (#59941)

# Objective

Zed normalizes all buffer text to `LF` internally, but was sending that
`LF`-normalized text to language servers even for `CRLF` files. This
caused servers such as ESLint (with a `linebreak-style` rule) to report
a false error on every line.

Fixes #38453

## Solution

Send the buffer's actual line endings to the language server instead:

- `didOpen` and full-document `didChange` now send
`text_with_line_endings()`, and incremental changes apply the buffer's
line ending to each edit.
- Normalize the line endings returning from the LSP before computing
changed regions
- This effectively incorporates the fix from #59151, which happens to be
the reason this change was [originally
reverted](https://github.com/zed-industries/zed/commit/1b6cde7032fea1ff38f885419ab4e79c4f8c3231).
As such, that PR should likely be integrated first.
- Detect when a buffer's line ending differs from what a server was last
sent and force a full-document resync, without this the server would
keep stale line endings, as the incremental change tracking does not
consider line ending differences.
- Route the `UpdateLineEnding` operation to `on_buffer_edited` so
toggling line endings via the status bar notifies the server immediately
rather than waiting for the file to be edited or reopened.



## Testing

- Did you test these changes? If so, how?
Yes, in addition to new unit test coverage, I used a test project with
ESLint configured with the `linebreak-style` rule set to enforce CRLF
line endings to verify that the LSP integration worked as expected.

- Are there any parts that need more testing?
The original reversion seems to have been due to a regression in which
LSP formatting would cause the editor to scroll to the bottom. I'm not
seeing this in my reproduction, and I believe this was due to a failure
to normalize line endings coming back from the LSP, but I don't know the
exact circumstances that led to the original reversion, so there might
be some additional things to test there.

- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
Not really! As mentioned above, configuring ESLint with the
`linebreak-style` rule is probably the easiest way to test.

- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
  I tested on Linux, but I don't believe it's relevant.

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

## Showcase



https://github.com/user-attachments/assets/881c5758-a5de-433c-8fd6-3cad7478aa90



---

Release Notes:

- Fixed an issue where language servers received incorrect line endings
for `CRLF` files, causing linters and formatters to report false errors.

---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>