Return suggested character parings

[ElliottStokes]

The character guide book includes mandatory and recommendations for which characters should or should not be paired with certain characters.

For example:

Acceptance Criteria:

• Reject assigning cards if the mandatory ones are not selected.
• In the return body include recommended characters to play with other characters

Technical Details:

• New SQL table which will track the mandatory card pairings
• New SQL table which will track the recommended card pairings
• New endpoint to only return suggestions for card pairings
• Update assignCards endpoints return a 400 error when mandatory pairings are not selected
• Update assignCards endpoint to return a response body with recommended pairings