feat: add torch plugin for iOS and Android (#3551)

* feat(barcode-scanner): add torch toggle

* feat: torch plugin

* fix

---------

Co-authored-by: Lucas Nogueira <lucas@tauri.app>

plugins/torch/src/error.rs

@@ -0,0 +1,28 @@
+// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: MIT
+
+use serde::{Serialize, ser::Serializer};
+
+/// Alias for the result type returned by this crate's functions.
+pub type Result<T> = std::result::Result<T, Error>;
+
+/// The error type returned by this crate's APIs. Serialized as its [`Display`](std::fmt::Display)
+/// string when it crosses the IPC boundary.
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    /// Failed to run a command on the mobile plugin implementation (Kotlin on Android, Swift on
+    /// iOS). This includes the native side rejecting the call, e.g. because the device has no
+    /// torch or the camera is held by another app.
+    #[error(transparent)]
+    PluginInvoke(#[from] tauri::plugin::mobile::PluginInvokeError),
+}
+
+impl Serialize for Error {
+    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        serializer.serialize_str(self.to_string().as_ref())
+    }
+}