Repeated requests caching

[guicassolato]

Authorino will currently repeat the entire identity → metadata → authorization pipeline on every request with "repeated" payload targeting a same API. Perhaps with some proper configuration options provided, it could cache the authorization response and speed up the return to the proxy.

This is not trivial and a minimal implementation would include:

• Enabled/disabled switch
• TTL of the cache keys (maybe set by default to the expiration of the access token when available)
• Hashing of the payload combining fixed (client creds, requested verb, URI, etc) and optional/additional (client IP, user-agent, etc) parts
• Auto-cleanup of the cache on API config refresh