Fine tune some items in the organization services

The following discussions from !138706 (merged) should be addressed:

• @dstull started a discussion: (+1 comment)

  note (non-blocking):

  Moved a handful of the other avatar models to centralize the avatarable specs here.

  Need a follow-up to do the same for the below possibly:

  • /app/models/achievements/achievment.rb
  • /app/models/projects/topic.rb

• @dstull started a discussion:

  note (non-blocking):

  Investigate in follow-up the use of hash for a response payload in CreateService

• @dstull started a discussion:

  note (non-blocking):

  Investigate in follow-up the use of hash for a response payload in CreateService

• @dstull started a discussion:

  note (non-blocking):

  Investigate the public surface area of Organizations::BaseService