feat: add api functions and actix webserver

src/types/app_state.rs

@@ -0,0 +1,7 @@
+use std::sync::Mutex;
+
+use crate::search::engine::SearchEngine;
+
+pub struct AppStateWithSearchEngine {
+    pub search_engine: Mutex<SearchEngine>, // <- Mutex is necessary to mutate safely across threads
+}

src/types/mod.rs

@@ -0,0 +1 @@
+pub mod app_state;