[Wi-Fi] Hide SoftKeyboard temporary when user tap the advanced button.

When tapping on the advanced button during configuring a network, some items in the expanded list are covered by IME keyboard, which may cause user to ignore them accidently.

To improve it, hide the IME temporary to let user can see most of them.

Bug: 78441374
Test: Use ShadowInputMethodManager to check if the keyboard is hide or not after tapping on the advance button.
Change-Id: I0677d96febc90c66d1cf6f98555bbb436a654660