zed: Fix no way to open local folder from remote window (#30954)

Closes #27642

Currently, the `Open (cmd-o)` action is used to open a local folder
picker when in a local project, and Zed's remote path modal in the case
of a remote project. While this looks intentional, there is now no way
to open a local project when you are in a remote project window. Neither
by shortcut, nor by UI, as the "Open Local Folder" button uses the same
`Open` action.

The reverse is not true, as we already have an `Open Remote
(ctrl-cmd-o)` action to open the remote modal, where you can select "Add
Folder" which opens the same Zed's remote path modal. This already works
in both local and remote window cases.

This PR makes two changes:
1. It changes `Open (cmd-o)` action such that it should always open the
local file picker regardless of which project is currently open, local
or remote. This way we have two non-ambiguios actions `Open` and `Open
Remote`.
2. It also changes the "Open a project" button (which shows up when no
project is open in the project panel) to open the recent modal (which
contains buttons to open either local or remote) instead of choosing on
behalf of the user.

P.S. If we want to open Zed's remote path modal directly, it should be
different action altogether. Not covered for now.

Release Notes:

- Fixed issue where "Open local folder" was not opening folder picker
when connected to a remote host.
- Added `from_existing_connection` flag to `OpenRemote` action to
directly open path picker for current connection, bypassing the Remote
Projects modal.

assets/keymaps/default-linux.json

@@ -512,6 +512,8 @@
       "alt-ctrl-o": "projects::OpenRecent",
       "alt-shift-open": "projects::OpenRemote",
       "alt-ctrl-shift-o": "projects::OpenRemote",
+      // Change to open path modal for existing remote connection by setting the parameter
+      // "alt-ctrl-shift-o": "["projects::OpenRemote", { "from_existing_connection": true }]",
       "alt-ctrl-shift-b": "branches::OpenRecent",
       "alt-shift-enter": "toast::RunAction",
       "ctrl-~": "workspace::NewTerminal",

assets/keymaps/default-macos.json

@@ -588,6 +588,7 @@
       // "alt-cmd-o": ["projects::OpenRecent", {"create_new_window": true }],
       "alt-cmd-o": "projects::OpenRecent",
       "ctrl-cmd-o": "projects::OpenRemote",
+      "ctrl-cmd-shift-o": ["projects::OpenRemote", { "from_existing_connection": true }],
       "alt-cmd-b": "branches::OpenRecent",
       "ctrl-~": "workspace::NewTerminal",
       "cmd-s": "workspace::Save",