Add --add/--new to control CLI behaviour (#9202)

When neither is specified, if you open a directory you get a new
workspace, otherwise files are added to your existing workspace.

With --new files are always opened in a new workspace
With --add directories are always added to an existing workspace

Fixes #9076
Fixes #4861
Fixes #5370

Release Notes:

- Added `-n/--new` and `-a/--add` to the zed CLI. When neither is
specified, if you open a directory you get a new workspace, otherwise
files are added to your existing workspace. With `--new` files are
always opened in a new workspace, with `--add` directories are always
added to an existing workspace.
([#9076](https://github.com/zed-industries/zed/issues/9096),
[#4861](https://github.com/zed-industries/zed/issues/4861),
[#5370](https://github.com/zed-industries/zed/issues/5370)).

crates/journal/src/journal.rs

@@ -102,7 +102,14 @@ pub fn new_journal_entry(app_state: Arc<AppState>, cx: &mut WindowContext) {
     cx.spawn(|mut cx| async move {
         let (journal_dir, entry_path) = create_entry.await?;
         let (workspace, _) = cx
-            .update(|cx| workspace::open_paths(&[journal_dir], app_state, None, cx))?
+            .update(|cx| {
+                workspace::open_paths(
+                    &[journal_dir],
+                    app_state,
+                    workspace::OpenOptions::default(),
+                    cx,
+                )
+            })?
             .await?;
 
         let opened = workspace