Fee scheme settings using configuration driven approach

[lostie]

The idea behind this is to move towards an approach that avoids having code like this:

def call
  ...
  return agfs_reform_categories if agfs_reform? || Offence.in_scheme_ten.include?(claim.offence)
  default_categories
end

def default_categories
  Settings.advocate_categories
end

def agfs_reform_categories
  Settings.agfs_reform_advocate_categories
end

def agfs_reform?
  claim.fee_scheme&.agfs? && claim.fee_scheme.version >= 10
end

in favour of:

# settings.yml
fee_schemes:
  agfs_9:
    advocate_categories: ['foo']
  agfs_10:
    advocate_categories: ['bar']
  agfs_11:
    advocate_categories: ['zzz']

# meta code just to illustrate the idea of what we're trying to do
def call
  ..
  claim.advocate_categories
  # which actually does 
  Settings['fee_schemes'][claim.fee_scheme]['advocate_categories']
end  

Where we always ask the claim which fee scheme its on and then the fee scheme has the associated information for it.