Add methods to JsUtility to wrap returned element references

[sbabcoc]

Element references returned by JavaScript functions are native WebElement objects, which means that we have no automatic recovery if references go stale. We should provide methods to enable implementers to wrap returned references in RobustWebElement objects.

This is especially useful for JavaScript functions that return lists of references. For this scenario, clients would supply the list of element references and an Xpath locator as a regular expression pattern that includes a placeholder for an index. An example of a scenario for this sort of method can be found in the OPCT project, in SearchResults.getSearchResultRows()

[sbabcoc]

The new implementation of JavaScript-based element search in RobustElementWrapper, and the implementation on FirefoxShadowRoot.findElements(), provide patterns for how this might work. However, the freeform nature of JavaScript functions precludes the provision of a bulletproof generic reference recovery mechanism.
However, it may be possible to create a JavaScript refresh context that retains the relationship between element references and the scripts that acquired them.