Add language toolchains (#19576)

This PR adds support for selecting toolchains for a given language (e.g.
Rust toolchains or Python virtual environments) with support for SSH
projects provided out of the box. For Python we piggy-back off of
[PET](https://github.com/microsoft/python-environment-tools), a library
maintained by Microsoft.
Closes #16421
Closes #7646

Release Notes:

- Added toolchain selector to the status bar (with initial support for
Python virtual environments)

crates/languages/src/yaml.rs

@@ -3,7 +3,8 @@ use async_trait::async_trait;
 use futures::StreamExt;
 use gpui::AsyncAppContext;
 use language::{
-    language_settings::AllLanguageSettings, LanguageServerName, LspAdapter, LspAdapterDelegate,
+    language_settings::AllLanguageSettings, LanguageServerName, LanguageToolchainStore, LspAdapter,
+    LspAdapterDelegate,
 };
 use lsp::LanguageServerBinary;
 use node_runtime::NodeRuntime;
@@ -92,6 +93,7 @@ impl LspAdapter for YamlLspAdapter {
     async fn workspace_configuration(
         self: Arc<Self>,
         delegate: &Arc<dyn LspAdapterDelegate>,
+        _: Arc<dyn LanguageToolchainStore>,
         cx: &mut AsyncAppContext,
     ) -> Result<Value> {
         let location = SettingsLocation {