refactor(shell)!: remove deprecated open API (#3604)

* refactor(shell)!: remove deprecated open API

`open` has been deprecated since 2.1.0 in favor of tauri-plugin-opener.
This removes:

- the `open` command and its `allow-open`/`deny-open` permissions
  (`shell:default` now grants nothing)
- the `plugins > shell > open` configuration; `init()` returns
  `TauriPlugin<R>` again
- `Shell::open`, the `tauri_plugin_shell::open` module and
  `Error::UnknownProgramName`
- the `open` JavaScript function
- the Android and iOS plugins, since `open` was their only command

* chore(examples): drop the now empty shell:default permission set

---------

Co-authored-by: Lucas Nogueira <lucas@crabnebula.dev>

plugins/shell/permissions/autogenerated/reference.md

@@ -5,13 +5,8 @@ shell functionality is exposed by default.
 
 #### Granted Permissions
 
-It allows to use the `open` functionality with a reasonable
-scope pre-configured. It will allow opening `http(s)://`,
-`tel:` and `mailto:` links.
-
-#### This default permission set includes the following:
-
-- `allow-open`
+Nothing is granted by default. Spawning processes must be explicitly
+allowed with a scope, see `allow-execute` and `allow-spawn`.
 
 ## Permission Table
 
@@ -77,32 +72,6 @@ Denies the kill command without any pre-configured scope.
 <tr>
 <td>
 
-`shell:allow-open`
-
-</td>
-<td>
-
-Enables the open command without any pre-configured scope.
-
-</td>
-</tr>
-
-<tr>
-<td>
-
-`shell:deny-open`
-
-</td>
-<td>
-
-Denies the open command without any pre-configured scope.
-
-</td>
-</tr>
-
-<tr>
-<td>
-
 `shell:allow-spawn`
 
 </td>