[#71] 🐌 Slow connection detection

[LahaLuhem]

This builds on #118 to implement #71.

Summary of changes

1. Added SlowConnectionConfig class
   • Use to configure the 'what is slow'
2. Updated InternetCheckResult to include responseTime field
   • Will be used to track the timing of the response of the result
3. Implementation in InternetConnection
   • Modified _checkReachabilityFor to measure and record response time
   • Updated internetStatus getter to check for slow connections when config is provided
   • Added two new methods for slow detection in both strict and non-strict modes
     1. _internetStatusWithSlowDetectionStrict(): Checks if all endpoints are successful, then checks if any are slow
     2. _internetStatusWithSlowDetectionNonStrict(): Checks for any successful endpoint, returns connected if fast connection found, slow if only slow connections found

Summary of behaviour

This makes the final behaviour as follows

• When slowConnectionConfig is null: Behaves as before with just connected/disconnected
• When slowConnectionConfig is provided
  • In strict mode: All endpoints must succeed. If any successful response exceeds the threshold, status is slow
  • In non-strict mode: Returns connected as soon as a fast connection is found, slow if only slow connections found, disconnected if none succeed
  • hasInternetAccess still returns true for both connected and slow statuses

Left to do

1. Add new unit tests for the slow detection