DX/Update connection error msgs

[databyjp]

This PR updates error messages for:

• The start-up REST connection error, which can occur at startup as the client checks for OIDC details
  • By asking whether Weaviate is running and reachable at {self.url}.
  • (at https://github.com/weaviate/weaviate-python-client/blob/dx/update-connection-error-msgs/weaviate/connect/v4.py#L241 oidc_url = self.url + self._api_version_path + "/.well-known/openid-configuration")
• gRPC health check errors, by
  • Distinguishing gRPC & REST connections for the user
  • Including the gRPC url/port in the error message & suggesting the user check those
  • Suggest whether there may be a firewall

[databyjp]

Tested by running this to simulate a slow/unresponsive connection:

import socket
import time

# Create a TCP/IP socket
server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_address = ('localhost', 12345)
server_socket.bind(server_address)
server_socket.listen(1)

print('Server listening on {}:{}'.format(*server_address))

while True:
    print('Waiting for a connection...')
    connection, client_address = server_socket.accept()
    try:
        print('Connection from', client_address)

        # Receive data and simulate a delay
        data = connection.recv(1024)
        print('Received:', data)
        time.sleep(100)  # Simulate 1 second delay

        # Send a response
        connection.sendall(b'Response from the server')
    finally:
        connection.close()

And various connections scenarios:

import time
import weaviate
from weaviate.classes.init import Timeout, AdditionalConfig, Auth
import time

def run_weaviate():
    for (port, grpc_port, timeout, auth) in [
        (8080, 50051, 2, None), # Correct, no auth
        (8080, 50051, 2, Auth.api_key("12345")), # Correct, wrong auth
        (12345, 50051, 2, None), # REST Black hole
        (8080, 12345, 2, None), # gRPC Black hole
        (1111, 50051, 2, None), # Incorrect REST
        (8080, 1111, 2, None), # Incorrect gRPC
    ]:
        print(f"\n")
        print(f"=" * 80)
        print(f"port={port}, grpc_port={grpc_port}, timeout={timeout}")
        print(f"=" * 80)
        print(f"\n")
        starttime = time.time()
        try:
            client = weaviate.connect_to_local(
                port=port,
                grpc_port=grpc_port,
                auth_credentials=auth,
                additional_config=AdditionalConfig(
                    timeout=Timeout(init=timeout, insert=5)  # Set grpc timeout to 2 seconds, rest timeout to 5 seconds
                )
            )

            assert client.is_ready()
            print("Weaviate is ready")
            client.close()
        except Exception as e:
            print(e)
        print("Time taken: ", time.time() - starttime)
    return True


if __name__ == '__main__':

    run_weaviate()