WifiConfiguration: Undeprecate WPA_PSK

This is needed for client mode operations for configuring WPA_PSK
networks. There is no alternative public value for WPA_PSK.
The intention was to deprecate usage of this value for AP
mode, but since we share the same object across client & AP mode
operations, we cannot mark this field deprecated.

Bug: 72332080
Test: make update-api
Change-Id: I75f675b630080d853422f945d7cbc37c5f205fde