feat(window-state): add js api, closes #254 (#309)

* feat(window-state): add js api, closes #254

* symlink tsconfig.json

* update symlink

* Update plugins/window-state/package.json

Co-authored-by: Fabian-Lars <fabianlars@fabianlars.de>

* Update Cargo.toml

* move to cmd.rs

* Update plugins/window-state/guest-js/index.ts

---------

Co-authored-by: Fabian-Lars <fabianlars@fabianlars.de>

plugins/window-state/src/cmd.rs

@@ -0,0 +1,28 @@
+use crate::{AppHandleExt, StateFlags, WindowExt};
+use tauri::{command, AppHandle, Manager, Runtime};
+
+#[command]
+pub async fn save_window_state<R: Runtime>(
+    app: AppHandle<R>,
+    flags: u32,
+) -> std::result::Result<(), String> {
+    let flags = StateFlags::from_bits(flags)
+        .ok_or_else(|| format!("Invalid state flags bits: {}", flags))?;
+    app.save_window_state(flags).map_err(|e| e.to_string())?;
+    Ok(())
+}
+
+#[command]
+pub async fn restore_state<R: Runtime>(
+    app: AppHandle<R>,
+    label: String,
+    flags: u32,
+) -> std::result::Result<(), String> {
+    let flags = StateFlags::from_bits(flags)
+        .ok_or_else(|| format!("Invalid state flags bits: {}", flags))?;
+    app.get_window(&label)
+        .ok_or_else(|| format!("Couldn't find window with label: {}", label))?
+        .restore_state(flags)
+        .map_err(|e| e.to_string())?;
+    Ok(())
+}