[Android] Add runtime core API copyBackForwardList

1 This class contains the back/forward list for a XWalkView.
XWalkView.copyBackForwardList() will return a copy of this class
used to inspect the entries in the list.
2 Add the API of XWalkView which is needed by the Cordova Container.
3 Implement BackForwardList and WebHistoryItem by wraping
org.chromium.content.browser.NavigationHistory class.
[Android] Add runtime core APIs saveState/restoreState

1 XWalkView.saveState() saves the state of the XWalkView to a
Bundle; XWalkView.restoreState() restores the state of the
XWalkView from a given Bundle.
2 Add the two APIs of XWalkView which are needed by the Cordova
Container.
3 Save/Restore the state of WebView to/from the given Bundle.
Use WebContents object as the state data.
[Android] Add saveState, restoreState test cases

Disable one test case as there is a blocking issue in
core test framework.