Add initial support for defining language server adapters in WebAssembly-based extensions (#8645)

This PR adds **internal** ability to run arbitrary language servers via
WebAssembly extensions. The functionality isn't exposed yet - we're just
landing this in this early state because there have been a lot of
changes to the `LspAdapter` trait, and other language server logic.

## Next steps

* Currently, wasm extensions can only define how to *install* and run a
language server, they can't yet implement the other LSP adapter methods,
such as formatting completion labels and workspace symbols.
* We don't have an automatic way to install or develop these types of
extensions
* We don't have a way to package these types of extensions in our
extensions repo, to make them available via our extensions API.
* The Rust extension API crate, `zed-extension-api` has not yet been
published to crates.io, because we still consider the API a work in
progress.

Release Notes:

- N/A

---------

Co-authored-by: Marshall <marshall@zed.dev>
Co-authored-by: Nathan <nathan@zed.dev>
Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/extension_api/build.rs

@@ -0,0 +1,15 @@
+fn main() {
+    let version = std::env::var("CARGO_PKG_VERSION").unwrap();
+    let out_dir = std::env::var("OUT_DIR").unwrap();
+
+    let mut parts = version.split(|c: char| !c.is_digit(10));
+    let major = parts.next().unwrap().parse::<u16>().unwrap().to_be_bytes();
+    let minor = parts.next().unwrap().parse::<u16>().unwrap().to_be_bytes();
+    let patch = parts.next().unwrap().parse::<u16>().unwrap().to_be_bytes();
+
+    std::fs::write(
+        std::path::Path::new(&out_dir).join("version_bytes"),
+        [major[0], major[1], minor[0], minor[1], patch[0], patch[1]],
+    )
+    .unwrap();
+}