Add `getInteractionObject` method for consistency with other questions and data reporting

[danielghost]

The getInteractionObject method is missing and would be required if added to data reporting for both xAPI and SCORM (adaptlearning/adapt-contrib-spoor#281).

[danielghost]

On further investgation of the pattern for the fill-in interaction type, the potential for multiple correct answers for each item could result in complex patterns to account for all permutations, restricting the ability to include this functionality.

For SCORM the LMS only has to cater for at least 5 patterns, which could easily be exceeded where multiple correct answers are used.

xAPI recommends not to use the pattern if all correct responses cannot be listed:

Where the criteria for a question are complex and correct responses cannot be exhaustively listed, Learning Record Providers are discouraged from using the "correctResponsesPattern" property.

[danielghost]

Added a commit to resolve this issue should this be a requirement we wish to include, as an LMS may cater for more patterns and xAPI doesn't have a limit.

Reopening for community to decide if this is something we wish to include, noting the potential restrictions in comments thread.