Fix IME soft keyboard for Bluetooth rename device dialog.

The soft keyboard should automatically pop up when the user selects
the Bluetooth rename device menu item. Fixed by calling
setSoftInputMode(SOFT_INPUT_STATE_ALWAYS_VISIBLE) on the Window
containing the AlertDialog before showing.

The device name field should also be a single line field, with the
Done button causing the device to be renamed. Set the "singleLine"
attribute in the layout XML to true, and added a
TextView.OnEditorActionListener to set the device name and dismiss
the dialog for EditorInfo.IME_ACTION_DONE.

Bug: 5342542
Bug: 5343354
Change-Id: I550d8e9a59395ad66f8a9c11d29c0f2ef278c196