[UBP] Free tier Balance Used and Usage page do not show correct credits used

[jldec]

The personal and team billing pages both show a progress indicator for "Balance Used" with actual usage against the usage limit.

The usage detail page (for individuals and teams) both show a similar total credits used for the current period.

These indicators should derive their "credits used" value from credits used since the last invoice/reset, instead of assuming a calendar billing cycle.

The calculation should mirror the logic used to compute "credits used" to show the usage limit 80% or limit exceeded notifications and prevent workspace starts.

[jldec]

Related to #14367

[geropl]

I think the idea here was instead of retrieving the limit value, make sure that the selected time range matches what we expect from the Billing page. 🤔

[geropl]

Steps to tackle this:

• fix "usage bar"
  • extend the GetStripeSubscriptionResponse to also contain billingPeriod information
  • make that available via JSON RPC
  • use those values in the BillingConfig view to set/calculate period start&end here (which will fix the display in the usage bar because we now select correctly)
• make "Usage view" select arbitrary dates
  • add parameters for date selection, e.g.: https://gitpod.io/t/gitpod/usage?start=...&end=...
  • if set, use those here
• make the "Usage View" link on the BillingConfig page set the start/end parameters based on the actual BillingCycle

[jldec]

Reported again today by early-access user here (interna) and by Gitpodder here (internal).