Implement GetAvailableTalentsAsync

[Niphyr]

Implement the ability to pull a list of all talents available to a specific class & spec.

The following information is required:

• Flag to differentiate class/spec nodes
• Talent Id
• Name
• Type (Single, Choice)
• If it's an entry node
• List of talents associated with the node, including:
• • Max ranks
• • Spell Id
• • Icon
• • Definition (to show rank tooltip)
• • Talent Type (Active, Passive)
• If it's a free node
• Required points to talent into the node
• Max ranks for the talent