Subscription tests and domain (#2209)

* Save work

* Subscriptions and trials domain

* Store family ID on customer

* Remove indirection of stripe calls

* Test simplifications

* Update brakeman

* Fix stripe tests in CI

* Update billing page to show subscription details

* Remove legacy columns

* Complete billing settings page

* Fix hardcoded plan name

* Handle subscriptions for self hosting mode

* Lint fixes

app/models/subscription.rb

@@ -0,0 +1,37 @@
+class Subscription < ApplicationRecord
+  TRIAL_DAYS = 14
+
+  belongs_to :family
+
+  # https://docs.stripe.com/api/subscriptions/object
+  enum :status, {
+    incomplete: "incomplete",
+    incomplete_expired: "incomplete_expired",
+    trialing: "trialing", # We use this, but "offline" (no through Stripe's interface)
+    active: "active",
+    past_due: "past_due",
+    canceled: "canceled",
+    unpaid: "unpaid",
+    paused: "paused"
+  }
+
+  validates :stripe_id, presence: true, if: :active?
+  validates :trial_ends_at, presence: true, if: :trialing?
+
+  class << self
+    def new_trial_ends_at
+      TRIAL_DAYS.days.from_now
+    end
+  end
+
+  def name
+    case interval
+    when "month"
+      "Monthly Plan"
+    when "year"
+      "Annual Plan"
+    else
+      "Free trial"
+    end
+  end
+end