zed_extension_api: Fork new version of extension API (#17795)

This PR forks a new version of the `zed_extension_api` in preparation
for new changes.

Release Notes:

- N/A

---------

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

crates/extension_api/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "zed_extension_api"
-version = "0.1.0"
+version = "0.2.0"
 description = "APIs for creating Zed extensions in Rust"
 repository = "https://github.com/zed-industries/zed"
 documentation = "https://docs.rs/zed_extension_api"
@@ -8,6 +8,9 @@ keywords = ["zed", "extension"]
 edition = "2021"
 license = "Apache-2.0"
 
+# Remove when we're ready to publish v0.2.0.
+publish = false
+
 [lints]
 workspace = true