Extract IOptionsContainer from Options

Extract IOptionsContainer from Options

- Create a separate interface that declares addOption(), and make
  Options implement it.
- Change methods that took an Options just to call addOption() to take
  an instance of the new interface instead of a full Options object.
- Adjust documentation.

This isolates callers that only provide options from other details of
the options implementation, and allows further refactoring (that will
provide more implementations for this same interface).

Change-Id: I26d3f03602a8edd130d05231b3b0ee14b598ec8e