perf: rewrite config parser to double the startup speed

[sxyazi]

Startup time matters!

Before - db0300c:

Started in 32.108125ms

Now - this PR:

Started in 16.268708ms

Both are measured in release mode, test script:

Details

--- a/yazi-fm/src/main.rs
+++ b/yazi-fm/src/main.rs
@@ -10,6 +10,7 @@ yazi_macro::mod_flat!(context executor logs panic root router signals term);

 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
+       let now = std::time::Instant::now();
        Panic::install();
        yazi_shared::init();

@@ -33,5 +34,6 @@ async fn main() -> anyhow::Result<()> {
        yazi_core::init();

        yazi_dds::serve();
+       println!("Started in {:?}", now.elapsed());
        app::App::serve().await
 }