Captive Portal on demand

[RFDarter]

Describe the problem you have/What new integration you would like
Add the possibility to start the captive_portal on demand from the web_server or even a GPIO pin.
Add the possibility do deactivate the captive_portal and start the web_server form the captive_portal
Make it possible to disconnect from a wifi network an start the ap with eighter the web_server or the captive_portal

Please describe your use case for this integration and alternatives you've tried:
Once you connected the device to a wifi network using the camptive portal there is no way to change to a different wifi network without shutting down the wifi the ESP is curently connected to, to force a start ot the ap and the captive portal.
Once connected to a wifi there is alo on way to make the device standalone anymore with using the ap insetead of connected to the wifi

Additional context