zed: Use CLI env for lang servers, tasks, terminal (#17075)

This changes the Zed CLI `zed` to pass along the environment to the Zed
project that it opens (if it opens a new one).

In projects, this CLI environment will now take precedence over any
environment that's acquired by running a login shell in a projects
folder.

The result is that `zed my/folder` now always behaves as if one would
run `zed --foreground` without any previous Zed version running.


Closes #7894
Closes #16293 

Related issues:
- It fixes the issue described in here:
https://github.com/zed-industries/zed/issues/4977#issuecomment-2305272027


Release Notes:

- Improved the Zed CLI `zed` to pass along the environment as it was on
the CLI to the opened Zed project. That environment is then used when
opening new terminals, spawning tasks, or language servers.
Specifically:
- If Zed was started via `zed my-folder`, a terminal spawned with
`workspace: new terminal` will inherit these environment variables that
existed on the CLI
- Specific language servers that allow looking up the language server
binary in the environments `$PATH` (such as `gopls`, `zls`,
`rust-analyzer` if configured, ...) will look up the language server
binary in the CLI environment too and use that environment when starting
the process.
- Language servers that are _not_ found in the CLI environment (or
configured to not be found in there), will be spawned with the CLI
environment in case that's set. That means users can do something like
`RA_LOG=info zed .` and it will be picked up the rust-analyzer that was
spawned.

Demo/explanation:



https://github.com/user-attachments/assets/455905cc-8b7c-4fc4-b98a-7e027d97cdfa

crates/cli/Cargo.toml

@@ -19,6 +19,7 @@ path = "src/main.rs"
 [dependencies]
 anyhow.workspace = true
 clap.workspace = true
+collections.workspace = true
 ipc-channel = "0.18"
 once_cell.workspace = true
 parking_lot.workspace = true

crates/cli/src/cli.rs

@@ -1,3 +1,4 @@
+use collections::HashMap;
 pub use ipc_channel::ipc;
 use serde::{Deserialize, Serialize};
 
@@ -15,6 +16,7 @@ pub enum CliRequest {
         wait: bool,
         open_new_workspace: Option<bool>,
         dev_server_token: Option<String>,
+        env: Option<HashMap<String, String>>,
     },
 }
 

crates/cli/src/main.rs

@@ -3,6 +3,7 @@
 use anyhow::{Context, Result};
 use clap::Parser;
 use cli::{ipc::IpcOneShotServer, CliRequest, CliResponse, IpcHandshake};
+use collections::HashMap;
 use parking_lot::Mutex;
 use std::{
     env, fs, io,
@@ -122,6 +123,7 @@ fn main() -> Result<()> {
         None
     };
 
+    let env = Some(std::env::vars().collect::<HashMap<_, _>>());
     let exit_status = Arc::new(Mutex::new(None));
     let mut paths = vec![];
     let mut urls = vec![];
@@ -149,12 +151,14 @@ fn main() -> Result<()> {
         move || {
             let (_, handshake) = server.accept().context("Handshake after Zed spawn")?;
             let (tx, rx) = (handshake.requests, handshake.responses);
+
             tx.send(CliRequest::Open {
                 paths,
                 urls,
                 wait: args.wait,
                 open_new_workspace,
                 dev_server_token: args.dev_server_token,
+                env,
             })?;
 
             while let Ok(response) = rx.recv() {