Implement dynamic validation on QA Pages

EE port: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9982

What does this MR do?

Closes gitlab-qa#280 (closed)

Implements a dynamic validation of pages during navigation (clicking and visiting).

• In a QA test, when we visit a page, allow the ability for the framework to check to see if "all" elements that are required, exist before continuing the test.
• In a QA test, when we click an element, we expect some action in the browser to occur. when we end up on a page, allow the framework to determine if we successfully landed on said page.

rel: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21310/diffs#aa1a0ef7aa4adb931975c7957ca887348673e90e

Does this MR meet the acceptance criteria?

• [] Changelog entry added, if necessary
• [] Documentation created/updated via this MR
• [] Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• [] Tested in all supported browsers
• [] Conforms to the code review guidelines
• [] Conforms to the merge request performance guidelines
• [] Conforms to the style guides
• [] Conforms to the database guides
• [] Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• [] Security reports checked/validated by reviewer