Support asynchronous methods in ICacheStore

[therealsujitk]

I'd like to use this package on the server side that doesn't support localStorage, so I'm using a custom cache API to store the access token and other constants required by this package. It's very cool that this package already supports writing your own cache implementation, however the current implementation doesn't support asynchronous methods. Here's an example of what I want to accomplish.

class CustomCachingStore implements ICacheStore {
  private readonly customCache = new CustomCache();

  get(key: string) {
    return await this.customCache.get(key);
  }

  set(key: string, value: string) {
    await this.customCache.set(key, value);
  }

  remove(key: string) {
    await this.customCache.delete(key);
  }
}