feat: android bundling, red/blue exe names, session cache (#3608)

* feat: android bundling

* fix: add hashing to exe names for red/blue exes

* feat: implement session cache for window restoration

packages/cli-config/src/lib.rs

@@ -67,6 +67,7 @@ pub const APP_TITLE_ENV: &str = "DIOXUS_APP_TITLE";
 #[deprecated(since = "0.6.0", note = "The CLI currently does not set this.")]
 #[doc(hidden)]
 pub const OUT_DIR: &str = "DIOXUS_OUT_DIR";
+pub const SESSION_CACHE_DIR: &str = "DIOXUS_SESSION_CACHE_DIR";
 
 /// Reads an environment variable at runtime in debug mode or at compile time in
 /// release mode. When bundling in release mode, we will not be running under the
@@ -277,3 +278,15 @@ pub fn out_dir() -> Option<PathBuf> {
         std::env::var(OUT_DIR).ok().map(PathBuf::from)
     }
 }
+
+/// Get the directory where this app can write to for this session that's guaranteed to be stable
+/// between reloads of the same app. This is useful for emitting state like window position and size
+/// so the app can restore it when it's next opened.
+///
+/// Note that this cache dir is really only useful for platforms that can access it. Web/Android
+/// don't have access to this directory, so it's not useful for them.
+///
+/// This is designed with desktop executables in mind.
+pub fn session_cache_dir() -> Option<PathBuf> {
+    std::env::var(SESSION_CACHE_DIR).ok().map(PathBuf::from)
+}