Refactor `wait` and `retry_*` methods

What does this MR do?

This refactors the Waiter and Retrier modules.

• Moves wait into the Retrier module as wait_until, and renames the max parameter to max_duration, to convey that its purpose is similar to retry_until.
• Combines the loop logic into a single private method that the different public wait/retry methods use.
• Allows retry_until to retry up to a certain maximum time limit, like wait_until, as well as the original functionality of waiting until a specified condition is met.
• Adds a retry_on_exception parameter to so that it's not necessary to nest wait/retry blocks if you want to do both.
• Adds a raise_on_failure parameter, which is the same as retry_until's exit_on_failure parameter, but now it can be used with wait_until.

See gitlab-qa#282 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content