Add initial support for defining language server adapters in WebAssembly-based extensions (#8645)

This PR adds **internal** ability to run arbitrary language servers via
WebAssembly extensions. The functionality isn't exposed yet - we're just
landing this in this early state because there have been a lot of
changes to the `LspAdapter` trait, and other language server logic.

## Next steps

* Currently, wasm extensions can only define how to *install* and run a
language server, they can't yet implement the other LSP adapter methods,
such as formatting completion labels and workspace symbols.
* We don't have an automatic way to install or develop these types of
extensions
* We don't have a way to package these types of extensions in our
extensions repo, to make them available via our extensions API.
* The Rust extension API crate, `zed-extension-api` has not yet been
published to crates.io, because we still consider the API a work in
progress.

Release Notes:

- N/A

---------

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

crates/activity_indicator/src/activity_indicator.rs

@@ -6,7 +6,7 @@ use gpui::{
     ParentElement as _, Render, SharedString, StatefulInteractiveElement, Styled, View,
     ViewContext, VisualContext as _,
 };
-use language::{LanguageRegistry, LanguageServerBinaryStatus};
+use language::{LanguageRegistry, LanguageServerBinaryStatus, LanguageServerName};
 use project::{LanguageServerProgress, Project};
 use smallvec::SmallVec;
 use std::{cmp::Reverse, fmt::Write, sync::Arc};
@@ -30,7 +30,7 @@ pub struct ActivityIndicator {
 }
 
 struct LspStatus {
-    name: Arc<str>,
+    name: LanguageServerName,
     status: LanguageServerBinaryStatus,
 }
 
@@ -58,13 +58,10 @@ impl ActivityIndicator {
         let this = cx.new_view(|cx: &mut ViewContext<Self>| {
             let mut status_events = languages.language_server_binary_statuses();
             cx.spawn(|this, mut cx| async move {
-                while let Some((language, event)) = status_events.next().await {
+                while let Some((name, status)) = status_events.next().await {
                     this.update(&mut cx, |this, cx| {
-                        this.statuses.retain(|s| s.name != language.name());
-                        this.statuses.push(LspStatus {
-                            name: language.name(),
-                            status: event,
-                        });
+                        this.statuses.retain(|s| s.name != name);
+                        this.statuses.push(LspStatus { name, status });
                         cx.notify();
                     })?;
                 }
@@ -114,7 +111,7 @@ impl ActivityIndicator {
         self.statuses.retain(|status| {
             if let LanguageServerBinaryStatus::Failed { error } = &status.status {
                 cx.emit(Event::ShowError {
-                    lsp_name: status.name.clone(),
+                    lsp_name: status.name.0.clone(),
                     error: error.clone(),
                 });
                 false
@@ -202,11 +199,12 @@ impl ActivityIndicator {
         let mut checking_for_update = SmallVec::<[_; 3]>::new();
         let mut failed = SmallVec::<[_; 3]>::new();
         for status in &self.statuses {
-            let name = status.name.clone();
             match status.status {
-                LanguageServerBinaryStatus::CheckingForUpdate => checking_for_update.push(name),
-                LanguageServerBinaryStatus::Downloading => downloading.push(name),
-                LanguageServerBinaryStatus::Failed { .. } => failed.push(name),
+                LanguageServerBinaryStatus::CheckingForUpdate => {
+                    checking_for_update.push(status.name.0.as_ref())
+                }
+                LanguageServerBinaryStatus::Downloading => downloading.push(status.name.0.as_ref()),
+                LanguageServerBinaryStatus::Failed { .. } => failed.push(status.name.0.as_ref()),
                 LanguageServerBinaryStatus::Downloaded | LanguageServerBinaryStatus::Cached => {}
             }
         }
@@ -214,34 +212,28 @@ impl ActivityIndicator {
         if !downloading.is_empty() {
             return Content {
                 icon: Some(DOWNLOAD_ICON),
-                message: format!(
-                    "Downloading {} language server{}...",
-                    downloading.join(", "),
-                    if downloading.len() > 1 { "s" } else { "" }
-                ),
+                message: format!("Downloading {}...", downloading.join(", "),),
                 on_click: None,
             };
-        } else if !checking_for_update.is_empty() {
+        }
+
+        if !checking_for_update.is_empty() {
             return Content {
                 icon: Some(DOWNLOAD_ICON),
                 message: format!(
-                    "Checking for updates to {} language server{}...",
+                    "Checking for updates to {}...",
                     checking_for_update.join(", "),
-                    if checking_for_update.len() > 1 {
-                        "s"
-                    } else {
-                        ""
-                    }
                 ),
                 on_click: None,
             };
-        } else if !failed.is_empty() {
+        }
+
+        if !failed.is_empty() {
             return Content {
                 icon: Some(WARNING_ICON),
                 message: format!(
-                    "Failed to download {} language server{}. Click to show error.",
+                    "Failed to download {}. Click to show error.",
                     failed.join(", "),
-                    if failed.len() > 1 { "s" } else { "" }
                 ),
                 on_click: Some(Arc::new(|this, cx| {
                     this.show_error_message(&Default::default(), cx)