Add new make-file-executable API for extensions (#10047)

This PR adds a new function, `make-file-executable`, to the Zed
extension API that can be used to mark a given file as executable
(typically the language server binary).

This is available in v0.0.5 of the `zed_extension_api` crate.

We also reworked how we represent the various WIT versions on disk to
make it a bit clearer what the version number entails.

Release Notes:

- N/A

---------

Co-authored-by: Max <max@zed.dev>

crates/extension_api/src/extension_api.rs

@@ -53,7 +53,7 @@ pub static ZED_API_VERSION: [u8; 6] = *include_bytes!(concat!(env!("OUT_DIR"), "
 mod wit {
     wit_bindgen::generate!({
         skip: ["init-extension"],
-        path: "./wit/0.0.4",
+        path: "./wit/since_v0.0.4",
     });
 }