Revert quick_configure/2 to WPA2, but add option

WPA3 support has been very problematic on some Nerves-supported hardware
to the point where it causes more harm than good. This change reverts
the `quick_configure/2` implementation to use WPA2 when a password is
supplied. If you have hardware that does support WPA3, it's possible to
use the generic WiFi configuration by updating the application
environment:

```
config :vintage_net_wifi, :quick_configure, &VintageNetWiFi.Cookbook.generic/2
```

Here's a short list of hardware support:

* All Raspberry Pi's handle the generic configuration fine, but don't
  support WPA3.
* The BeagleBones with built-in WiFi using the WiLink8 module will
  try to use WPA3 whenever it's available, but fail to connect.
* GRiSP2 won't connect to WPA2 networks with the generic configuration
  even though WPA3 isn't in use at all.
* The NXP 88W8987 appears to work perfectly with the generic
  configuration and connects to both WPA3 and WPA2 APs

README.md

@@ -41,7 +41,7 @@ end
 The easiest way to configure WiFi is to using
 `VintageNetWiFi.quick_configure/2`. For example:
 
-```
+```elixir
 iex> VintageNetWiFi.quick_configure("my_access_point", "secret_passphrase")
 :ok
 ```
@@ -56,6 +56,9 @@ The second easiest way to create WiFi configurations is to use the helper
 functions in `VintageNetWiFi.Cookbook`. Check out the module documentation for
 the various configurations.
 
+See the `VintageNetWiFi.quick_configure/2` documentation for details on WPA3
+support.
+
 ## Advanced usage
 
 WiFi network interfaces typically have names like `"wlan0"` or `"wlan1"` when

lib/vintage_net_wifi.ex

@@ -843,6 +843,18 @@ defmodule VintageNetWiFi do
   other special configuration handling, you'll need to call
   `VintageNet.configure/3` instead. See `VintageNetWiFi.Cookbook` for help with
   creating configurations or manually construct the configuration map.
+
+  > #### WiFi Authentication {: .info}
+  >
+  > VintageNetWiFi doesn't know whether the WiFi hardware you're using fully
+  > supports WPA3 authentication. To avoid hard to understand errors,
+  > `quick_configure/2` defaults to WPA2. If you have hardware that supports
+  > WPA3 and would like to use WPA2/WPA3 generic configurations, update your
+  > `config.exs` to:
+  >
+  > ```
+  > config :vintage_net_wifi, :quick_configure, &VintageNetWiFi.Cookbook.generic/2
+  > ```
   """
   @spec quick_configure(String.t(), String.t() | nil) :: :ok | {:error, term()}
   def quick_configure(ssid, passphrase \\ nil)
@@ -855,7 +867,10 @@ defmodule VintageNetWiFi do
   end
 
   def quick_configure(ssid, passphrase) do
-    with {:ok, config} <- Cookbook.generic(ssid, passphrase) do
+    cookbook_strategy =
+      Application.get_env(:vintage_net_wifi, :quick_configure, &Cookbook.wpa_psk/2)
+
+    with {:ok, config} <- cookbook_strategy.(ssid, passphrase) do
       VintageNet.configure("wlan0", config)
     end
   end