FilesApp quickview: test to ensure that info box opens/closes on enter key

* Added quickview integration test pressEnterOnInfoBoxToOpenClose.
* Updated test.util.sync.deepQueryAllElements to accept targetQuery
  as either string or !Array<string>.
* Changed RemoteCall waitForElement* functions to call
  deepQueryAllElements to allow for usage with nested elements.
* Updated javadoc on RemoteCall functions to show which already
  support query as string|!Array<string>.


Bug: 893093
Change-Id: I7c542e7a2bc914e16fa8142fb696f5b3fe370752
Reviewed-on: https://chromium-review.googlesource.com/c/1345693
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610326}
4 files changed