cloud billing customer creation and reporting

[pjain1]

This includes - Creating a customer in external billing system on new org creation and assigning a billing plan to it. Plan metadata configured in the billing system should have quotas that will be fetched to be enforced as well reportable metric names. These metrics name will directly corresponds to the apis in the metrics project to fetch the corresponding usage. Usage reporter will use the apis to report usage to the billing system.

Next -

• [ ] Enforce usage limits especially managed data bytes, will go into reconciler
• [x] Create metrics APIs in metrics project that will be used to fetch usage
• [x] APIs for UI to get list of public plans, current subscriptions for a customer and change plan for a customer
• [x] Rill cli cmds for the same
• [x] Handling of trail period and subscription end in web-admin, APIs for this, will need product input