feat: async cache.read()/write(), remove .has()

src/cache/cache.ts

@@ -1,5 +1,4 @@
 export interface Cache<T> {
-  write (key: string, value: T): void;
-  read (key: string): T | undefined;
-  has (key: string): boolean;
+  write (key: string, value: T): void | Promise<void>;
+  read (key: string): T | undefined | Promise<T | undefined>;
 }

src/cache/lru.ts

@@ -42,10 +42,6 @@ export class LRU<T> implements Cache<T> {
     return value
   }
 
-  has (key: string): boolean {
-    return !!this.cache[key]
-  }
-
   remove (key: string) {
     const node = this.cache[key]
     node.prev.next = node.next