[WifiNetworkSelector] User-selected network is sufficient for a while

Skip autojoin for the first few seconds of a user-initiated connection.

This avoids early disconnection before the user has had a chance to
respond to a no-internet or limited internet dialog, and allows some
additional time for validation to succeed in case the dialog is not
noticed.

This effectively restores change-id I0a06135afef1876af385829d131a0e52b1884900,
which was removed in Id232b59a546271d7f0798bc6a85ca6ccd65621e9.

The duration is configurable.

Bug: 147751334
Test: atest WifiNetworkSelectorTest
Change-Id: I18c4fbbe5ceeb7510cfcec8d3c8cdebb8ef0f88d
4 files changed