Add/Remove users Google Workspace licences

Work in Progress:

• Use misAffiliation from Lookup to determine users need licensing
• Get users already licensed in Google (and with which SKU)
• Compare both to determine who to remove and who to add
• Check / Limit number of changes
• Remove licence assignments for those to remove (keep tally of available licenses in each SKU)
• Add license assignments for those to add (using tally to know when to change SKU)

Config needs for our domain:

# Details about Licensing assignment
licensing:
  # Customer ID
  customer_id: {redacted - not sure this is a secret}
  # Product ID:
  product_id: 101031
  # Dict of SKU IDs with their maximum size, available for users to be assigned to
  licensed_skus:
    "1010310008": 37600
    "1010310009": 9400

No way to test this with gdev as it has no subscriptions. Would be handy to have two - one smaller than the number of users we sync to it (soon to be uis-members, currently uis-devops*) so filling one up can be tested.

Closes: #33 (closed)