Restore manganis optimizations (#3195)

* Create a crate for constant serialization of config structs for manganis
* use SerializeConst for the image asset builder
* switch to a declarative macro for assets
* add serializable options for each asset type
* implement the new manganis macro
* optimize assets in the CLI
* Fix assets with dioxus formattable
* reduce fuzzing test limits
* use the new syntax in examples
* fix avif support
* Fix manganis doc tests
* cache asset optimization
* Split out asset and bundled asset
* make hash pointer width independent
* Fix manganis macro docs
* add constvec::is_empty method to fix clippy lint
* remove nasm feature
* simplify test_rsplit_once test so typos passes
* revert example change from clippy fix
* always accept unix paths
* fix windows path seperator
* fix folder asset hash
* Optimize assets in a blocking task
* Fix asset options docs
* Document Asset and BundledAsset
* simplify the linker macro a bit
* add more docs to AssetParser expansion
* add image format helpers
* Split by  both unix and windows path separators and take the smallest one

packages/cli/src/assets/folder.rs

@@ -0,0 +1,41 @@
+use std::path::Path;
+
+use rayon::iter::{IntoParallelRefIterator, ParallelIterator};
+
+use super::file::process_file_to;
+
+/// Process a folder, optimizing and copying all assets into the output folder
+pub fn process_folder(source: &Path, output_folder: &Path) -> anyhow::Result<()> {
+    // Create the folder
+    std::fs::create_dir_all(output_folder)?;
+
+    // Then optimize children
+    let files: Vec<_> = std::fs::read_dir(source)
+        .into_iter()
+        .flatten()
+        .flatten()
+        .collect();
+
+    files.par_iter().try_for_each(|file| {
+        let file = file.path();
+        let metadata = file.metadata()?;
+        let output_path = output_folder.join(file.strip_prefix(source)?);
+        if metadata.is_dir() {
+            process_folder(&file, &output_path)
+        } else {
+            process_file_minimal(&file, &output_path)
+        }
+    })?;
+
+    Ok(())
+}
+
+/// Optimize a file without changing any of its contents significantly (e.g. by changing the extension)
+fn process_file_minimal(input_path: &Path, output_path: &Path) -> anyhow::Result<()> {
+    process_file_to(
+        &manganis_core::AssetOptions::Unknown,
+        input_path,
+        output_path,
+    )?;
+    Ok(())
+}