Attempt connection to configured Wi-Fi without launching AP on failure

[rousveiga]

Hello,
I'd like to use this in the following way:

• Start the AP on demand by pressing a button (I know I can do this using startConfigPortal).
• On every boot, try to connect to the configured Wi-Fi. If the connection fails, or there is not a saved Wi-Fi, do not start the AP; instead, proceed with the program without connecting to Wi-Fi.

I know I can do this with the Wifi.h library; however, is there a way to do it using only WifiManager? It doesn't seem like such an uncommon feature.