wifi: Add support for multiple networks and auto-connect

[krish2718]

Is your feature request related to a problem? Please describe.
Every time a new connection request is made previous networks are removed (at least in WPA supplicant, unsure about offloaded Wi-Fi), this blocks adding multiple networks and also causes problem if we want to set any out-of-band (wpa_cli) network specific configuration.

Describe the solution you'd like
WPA supplicant has the ability to support multiple networks, so, we can

In Wi-Fi stack

1. Add an (API, Kconfig, Shell) for managing multiple networks wifi_net, with op: add/del/show(no args, name and priority as arguments.
2. Add an (API, Kconfig, Shell) for auto-connecting wifi_auto_connect
3. Extend (API,Shell) for wifi connect to take a parameter, prune which removes all previous added networks (enabled by default)

in WPA supplicant

1. remove_network from the connect only if prune == 1

Describe alternatives you've considered
NA

Additional context
This would also help in WFA certification where a mixture of wpa_cli and wifi shells are used e.g.,

Today we cannot do below for WPA3 11.1 (thanks @MaochenWang1 for bringing this up)

1. wpa_cli set domain_match
2. wifi connect

As #2 removes the network. But with this feature below should work

1. wifi_net add <SSID> 0 -> 2 is network ID
2. wifi list_networks
3. wpa_cli set 2 domain_match
4. wifi connect --networkid 2 --prune=0 or wifi auto_connect