[WIP] Use trial period on regular plan instead of trial plan

[tdrivas]

Current Approach
Currently, we create two separate subscriptions:

• A Trial Subscription (is_trial=True) that lasts for TRIAL_PERIOD_DAYS.
• A Paid Subscription that is created after the trial expires.

Problems with this approach:

• Handling multiple subscriptions for one user
• Extra logic to fetch, cancel or update trial and regular subscriptions separately.

New Approach

• User asks for a trial subscription
• if the user has no remaining organization trials, no subscription is created
• Otherwise, a subscription object is being created including, among others, a trial_plan, a regular plan and a default number of trial days.
• The trial subscription becomes active until the end of the trial.
• When the trial ends and depending on the user input (payment method), the subscription update its status (ACTIVE_ * / INACTIVE_ *)

[duke-nyuki]

Task linked: QF-2912 Use trial period on regular plan instead of trial plan

[suricactus]

Don't you need to add the admin methods for these two, similar to account__link?

[tdrivas]

My approach is for the list_display to show only the active plan. Since we already have the property plan in the model we can get only the active once. The reasons behind this approach is that it saves space, makes UI cleaner and still allows admins to differentiate trial status via the is_trialing column. If admin wants to see both the regular and trial plans separately, we could add filters.

[suricactus]

ok, let's discuss it tomorrow. I thought if a column does not exist, as in our case trial_plan__link column does not exist, we need to write a get_trial_plan__link method, but I guess I am wrong.