feat(back): Implement cache management

[spy4x]

Parts:

• CacheService (to wrap @Inject(CACHE_MANAGER) private readonly cache: Cache and it's methods)
  • async get<T>(key: string): Promise<T>
  • async set(key: string, value: Object, ttl: CacheTTL): Promise<void>
  • wrap(key: string, asyncFn: Function, ttl: CacheTTL): Function
  • async purge(url: string, shouldPreload = false): Promise<void>
  • async preload(url: string): Promise<void>