Remove dev servers (#19638)

TODO:

- [ ] Check that workspace migration worked
- [ ] Add server migrations and make sure SeaORM files are in sync
(maybe?)

Release Notes:

- N/A

---------

Co-authored-by: Conrad <conrad@zed.dev>
Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>

crates/zed/Cargo.toml

@@ -36,7 +36,6 @@ command_palette.workspace = true
 command_palette_hooks.workspace = true
 copilot.workspace = true
 db.workspace = true
-dev_server_projects.workspace = true
 diagnostics.workspace = true
 editor.workspace = true
 env_logger.workspace = true
@@ -52,7 +51,6 @@ git.workspace = true
 git_hosting_providers.workspace = true
 go_to_line.workspace = true
 gpui = { workspace = true, features = ["wayland", "x11", "font-kit"] }
-headless.workspace = true
 http_client.workspace = true
 image_viewer.workspace = true
 inline_completion_button.workspace = true