get more information about failed connect() to the caller

[vladak]

When connect() fails due to repeated failures, it throws RuntimeError:

Adafruit_CircuitPython_MiniMQTT/adafruit_minimqtt/adafruit_minimqtt.py

Lines 269 to 279 in 67e0ade

	try:
	sock.connect((connect_host, port))
	except MemoryError:
	sock.close()
	sock = None
	except OSError:
	sock.close()
	sock = None
	if sock is None:
	raise RuntimeError("Repeated socket failures")

This is not very useful for the caller. Some suggestions:

• rethrow the last exception
• wrap the exceptions raised by connect() into RuntimeError exception (or maybe used dedicated exception)
• add some info about the problem to the RuntimeError text (including how many times it tried)