WifiConfigStore: Support more than 1 shared store file

This is in preparation to move softap configuration to WifiConfigStore.

Bug: 144487256
Test: atest com.android.server.wifi
Change-Id: I42836a06b97b8539a70e71cfee8ec1d25579c3d9
4 files changed
tree: c0545af7291509af21f45eb884de187839040e35
  1. service/
  2. PREUPLOAD.cfg