Provide wasm extensions with APIs needed for using pre-installed LSP binaries (#9085)

In this PR, we've added two new methods that LSP extensions can call:
* `shell_env()`, for retrieving the environment variables set in the
user's default shell in the worktree
* `which(command)`, for looking up paths to an executable (accounting
for the user's shell env in the worktree)

To test this out, we moved the `uiua` language support into an
extension. We went ahead and removed the built-in support, since this
language is extremely obscure. Sorry @mikayla-maki. To continue coding
in Uiua in Zed, for now you can `Add Dev Extension` from the extensions
pane, and select the `extensions/uiua` directory in the Zed repo. Very
soon, we'll support publishing these extensions so that you'll be able
to just install it normally.

Release Notes:

- N/A

---------

Co-authored-by: Marshall <marshall@zed.dev>

extensions/uiua/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "zed_uiua"
+version = "0.0.1"
+edition = "2021"
+publish = false
+license = "Apache-2.0"
+
+[lints]
+workspace = true
+
+[dependencies]
+zed_extension_api = { path = "../../crates/extension_api" }
+
+[lib]
+path = "src/uiua.rs"
+crate-type = ["cdylib"]

extensions/uiua/extension.toml

@@ -0,0 +1,13 @@
+id = "uiua"
+name = "Uiua"
+description = "Uiua support for Zed"
+version = "0.0.1"
+authors = ["Max Brunsfeld <max@zed.dev>"]
+
+[language_servers.uiua]
+name = "Uiua LSP"
+language = "Uiua"
+
+[grammars.uiua]
+repository = "https://github.com/shnarazk/tree-sitter-uiua"
+commit = "21dc2db39494585bf29a3f86d5add6e9d11a22ba"

extensions/uiua/languages/uiua/config.toml

@@ -0,0 +1,11 @@
+name = "Uiua"
+grammar = "uiua"
+path_suffixes = ["ua"]
+line_comments = ["# "]
+autoclose_before = ")]}\""
+brackets = [
+    { start = "{", end = "}", close = true, newline = false},
+    { start = "[", end = "]", close = true, newline = false },
+    { start = "(", end = ")", close = true, newline = false },
+    { start = "\"", end = "\"", close = true, newline = false, not_in = ["string"] },
+]

extensions/uiua/languages/uiua/highlights.scm

@@ -0,0 +1,50 @@
+[
+  (openParen)
+  (closeParen)
+  (openCurly)
+  (closeCurly)
+  (openBracket)
+  (closeBracket)
+] @punctuation.bracket
+
+[
+  (branchSeparator)
+  (underscore)
+] @constructor
+; ] @punctuation.delimiter
+
+[ (character) ] @constant.character
+[ (comment) ] @comment
+[ (constant) ] @constant.numeric
+[ (identifier) ] @variable
+[ (leftArrow) ] @keyword
+[ (function) ] @function
+[ (modifier1) ] @operator
+[ (modifier2) ] @operator
+[ (number) ] @constant.numeric
+[ (placeHolder) ] @special
+[ (otherConstant) ] @string.special
+[ (signature) ] @type
+[ (system) ] @function.builtin
+[ (tripleMinus) ] @module
+
+; planet
+[
+  "id"
+  "identity"
+  "∘"
+  "dip"
+  "⊙"
+  "gap"
+  "⋅"
+] @tag
+
+[
+  (string)
+  (multiLineString)
+] @string
+
+; [
+;   (deprecated)
+;   (identifierDeprecated)
+; ] @warning

extensions/uiua/languages/uiua/indents.scm

@@ -0,0 +1,3 @@
+[
+  (array)
+] @indent

extensions/uiua/src/uiua.rs

@@ -0,0 +1,27 @@
+use zed_extension_api::{self as zed, Result};
+
+struct UiuaExtension;
+
+impl zed::Extension for UiuaExtension {
+    fn new() -> Self {
+        Self
+    }
+
+    fn language_server_command(
+        &mut self,
+        _config: zed::LanguageServerConfig,
+        worktree: &zed::Worktree,
+    ) -> Result<zed::Command> {
+        let path = worktree
+            .which("uiua")
+            .ok_or_else(|| "uiua is not installed".to_string())?;
+
+        Ok(zed::Command {
+            command: path,
+            args: vec!["lsp".to_string()],
+            env: Default::default(),
+        })
+    }
+}
+
+zed::register_extension!(UiuaExtension);