Aggregator-api collector auth token hash changes

[jbr]

Alongside DAP-07, Janus leaders will be accepting hashed collector auth tokens instead of a raw token. In order to accommodate this,

• #560
• #562
• #564
• #570
• #566
• #567
• #568

in the above, "+TokenHash tasks" are defined as "tasks for which the leader has opted into the TokenHash feature"

[tgeoghegan]

We opted to name the feature TokenHash for consistency with other camel case strings in the aggregator API configuration message.