Add OCaml support (#6929)

This pull request implements support for the [OCaml
Language](https://ocaml.org/).

### Additions
- [x]
[tree-sitter-ocaml](https://github.com/tree-sitter/tree-sitter-ocaml)
grammar
- [x] Highlight, Indents, Outline queries
- [x] A new file icon for .ml(i) files. Based on
[ocaml/ocaml-logo](https://github.com/ocaml/ocaml-logo/blob/master/Colour/SVG/colour-transparent-icon.svg)
- [x] LSP Integration with
[ocaml-language-server](https://github.com/ocaml/ocaml-lsp)
- [x] Completion Labels
- [x] Symbol Labels

### Bug Fixes
- [x] Improper parsing of LSP headers. 

### Missing [will file a separate issue]
- Documentation on completionItem, requires: `completionItem/resolve`
with support for `documentation` as a provider.

### Screenshots

<details><summary>Zed</summary>
<img width="1800" alt="Screenshot 2024-02-01 at 03 33 20"
src="https://github.com/zed-industries/zed/assets/69181766/e17c184e-203e-40c3-a08f-4de46226b79c">
</details>

Release Notes:
- Added OCaml Support
([#5316](https://github.com/zed-industries/zed/issues/5316)).

> [!NOTE]
> Partially completes #5316 
> To complete #5316:
> 1. addition of a reason tree-sitter grammar.
> 2. opam/esy integration, however it may be better as it's own plugin.

crates/lsp/src/lsp.rs

@@ -332,11 +332,36 @@ impl LanguageServer {
             };
 
             let header = std::str::from_utf8(&buffer)?;
-            let message_len: usize = header
+            let mut segments = header.lines();
+
+            let message_len: usize = segments
+                .next()
+                .context("unable to find the first line of the LSP message header")?
                 .strip_prefix(CONTENT_LEN_HEADER)
-                .ok_or_else(|| anyhow!("invalid LSP message header {header:?}"))?
-                .trim_end()
-                .parse()?;
+                .context("invalid LSP message header")?
+                .parse()
+                .with_context(|| {
+                    format!(
+                        "failed to parse Content-Length of LSP message header: {}",
+                        header
+                    )
+                })?;
+
+            if let Some(second_segment) = segments.next() {
+                match second_segment {
+                    "" => (), // Header end
+                    header_field if header_field.starts_with("Content-Type:") => {
+                        stdout.read_until(b'\n', &mut buffer).await?;
+                    }
+                    _ => {
+                        anyhow::bail!(
+                            "expected a Content-Type header field or a header ending CRLF, got {second_segment:?}"
+                        );
+                    }
+                }
+            } else {
+                anyhow::bail!("unable to find the second line of the LSP message header");
+            }
 
             buffer.resize(message_len, 0);
             stdout.read_exact(&mut buffer).await?;