Highlight adjacency list rows in BFS and DFS model solution

[ttaiv]

Adjacency list representation was added in pull request Aalto-LeTech/jsav-exercise-recorder#260. Model answer could be further improved by adding the adjacency list to it and highlighting the current node from the list at each step.

• Add adjacency list to model solution
• Highlight the currently relevant row

Originally posted by @ttaiv in #180