`zed --new ssh://host/path/to/file` only created a new window on the
first call. Subsequent invocations silently reused the existing SSH
workspace for the same host, which then tried to open the new path
against the existing worktree and surfaced a
`DevServerProjectPathDoesNotExist` popup when the path didn't belong to
any open worktree.

The CLI correctly translated `--new` to `OpenBehavior::AlwaysNew`, but
the URL branch of `handle_cli_connection` dropped the `open_behavior`.
`handle_open_request` then called `open_remote_project` (and
`open_paths_with_positions` for `file://`) with
`OpenOptions::default()`, which is `WorkspaceMatching::MatchExact`, so
any existing SSH window for the same host won the match. The issue
applies to `file://` URLs and `-a` / `-e` / `--reuse` for URL-shaped
arguments in general; `--new` was just the most visible symptom.

The fix is making sure the translation of `OpenRequest` is uniform
across plain paths and URL-shaped arguments.

Closes #52679.

Release Notes:

- Fixed `zed --new ssh://host/path` reusing an existing SSH window
instead of opening a new one. This also applied to other URL-shaped path
arguments.