Extract TOML support into an extension (#9940)

This PR extracts TOML support into an extension and removes the built-in
TOML support from Zed.

There's a small workaround necessary in order for us to set the file
permissions on the `taplo` binary so that it can be run. Eventually
we'll want to build this into the extension API, but for now we're just
hard-coding it on the host side.

Release Notes:

- Removed built-in support for TOML, in favor of making it available as
an extension. The TOML extension will be suggested for download when you
open a `.toml` or `Cargo.lock` file.

crates/extension/src/extension_lsp_adapter.rs

@@ -58,7 +58,7 @@ impl LspAdapter for ExtensionLspAdapter {
 
             // TODO: Eventually we'll want to expose an extension API for doing this, but for
             // now we just manually set the file permissions for extensions that we know need it.
-            if self.extension.manifest.id.as_ref() == "zig" {
+            if ["toml", "zig"].contains(&self.extension.manifest.id.as_ref()) {
                 #[cfg(not(windows))]
                 {
                     use std::fs::{self, Permissions};