WifiConfiguration: Add @hide method to set security params

Setting of these security params is duplicated in multiple parts of the
wifi stack. So, centralize this.

a) Move the security type enum from ScanResultMatchInfo class internally
into WifiConfiguration. (Note: Values don't change, just the name & location
since this is being persisted in multiple places)
b) Add a helper method to set the various security params required for
each security type.

Also, removed setting defaults in WifiNetworkSpecifier &
WifiNetworkSuggestion. This will anyway be handled by WifiConfigManager
on network addition. There is no need to replicate this in the API
surface.

Bug: 124071722
Test: ./frameworks/base/wifi/tests/runtests.sh
Change-Id: I382c497dfe331ee59f3560a8272b0e4ecf6ff8fc