New revision of the Assistant Panel (#10870)

This is a crate only addition of a new version of the AssistantPanel.
We'll be putting this behind a feature flag while we iron out the new
experience.

Release Notes:

- N/A

---------

Co-authored-by: Nathan Sobo <nathan@zed.dev>
Co-authored-by: Antonio Scandurra <me@as-cii.com>
Co-authored-by: Conrad Irwin <conrad@zed.dev>
Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>
Co-authored-by: Antonio Scandurra <antonio@zed.dev>
Co-authored-by: Nate Butler <nate@zed.dev>
Co-authored-by: Nate Butler <iamnbutler@gmail.com>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Co-authored-by: Max <max@zed.dev>

script/zed-local

@@ -147,7 +147,7 @@ setTimeout(() => {
     }
     spawn(binaryPath, i == 0 ? args : [], {
       stdio: "inherit",
-      env: {
+      env: Object.assign({}, process.env, {
         ZED_IMPERSONATE: users[i],
         ZED_WINDOW_POSITION: position,
         ZED_STATELESS: isStateful && i == 0 ? "1" : "",
@@ -157,9 +157,8 @@ setTimeout(() => {
         ZED_ADMIN_API_TOKEN: "secret",
         ZED_WINDOW_SIZE: size,
         ZED_CLIENT_CHECKSUM_SEED: "development-checksum-seed",
-        PATH: process.env.PATH,
         RUST_LOG: process.env.RUST_LOG || "info",
-      },
+      }),
     });
   }
 }, 0.1);