Revert "WifiConfigStore: Remove legacy modules"

This reverts commit a83bd15861ae7175b1f62bc2dc8de63e0dbe808e.

Bug: 31041781
Test: Unit tests
Test: Upgraded a device from N to P and ensured that the saved networks
are not lost.
Test: Will send for integration tests
Change-Id: I62ba62579b5a2004b1b854a53f4d465ee806a440
9 files changed