Remove duplicated code for unchanged parts of different extension API versions (#10218)

Release Notes:

- N/A

---------

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

crates/extension_api/wit/since_v0.0.4/extension.wit

@@ -1,35 +1,11 @@
 package zed:extension;
 
 world extension {
+    use github.{github-release, github-release-options};
+    use platform.{os, architecture};
+
     export init-extension: func();
 
-    record github-release {
-        version: string,
-        assets: list<github-release-asset>,
-    }
-
-    record github-release-asset {
-        name: string,
-        download-url: string,
-    }
-
-    record github-release-options {
-        require-assets: bool,
-        pre-release: bool,
-    }
-
-    enum os {
-        mac,
-        linux,
-        windows,
-    }
-
-    enum architecture {
-        aarch64,
-        x86,
-        x8664,
-    }
-
     enum downloaded-file-type {
         gzip,
         gzip-tar,

crates/extension_api/wit/since_v0.0.4/github.wit

@@ -0,0 +1,28 @@
+interface github {
+    /// A GitHub release.
+    record github-release {
+        /// The version of the release.
+        version: string,
+        /// The list of assets attached to the release.
+        assets: list<github-release-asset>,
+    }
+
+    /// An asset from a GitHub release.
+    record github-release-asset {
+        /// The name of the asset.
+        name: string,
+        /// The download URL for the asset.
+        download-url: string,
+    }
+
+    /// The options used to filter down GitHub releases.
+    record github-release-options {
+        /// Whether releases without assets should be included.
+        require-assets: bool,
+        /// Whether pre-releases should be included.
+        pre-release: bool,
+    }
+
+    /// Returns the latest release for the given GitHub repository.
+    latest-github-release: func(repo: string, options: github-release-options) -> result<github-release, string>;
+}

crates/extension_api/wit/since_v0.0.4/platform.wit

@@ -0,0 +1,24 @@
+interface platform {
+    /// An operating system.
+    enum os {
+        /// macOS.
+        mac,
+        /// Linux.
+        linux,
+        /// Windows.
+        windows,
+    }
+
+    /// A platform architecture.
+    enum architecture {
+        /// AArch64 (e.g., Apple Silicon).
+        aarch64,
+        /// x86.
+        x86,
+        /// x86-64.
+        x8664,
+    }
+
+    /// Gets the current operating system and architecture.
+    current-platform: func() -> tuple<os, architecture>;
+}