Premium Apps: SKU and Entitlement fields

[colinloretz]

Addressing docs for Entitlements (#6476)

The subscription_id, promotion_id, deleted, and gift_code_flags fields are undocumented.

• Added deleted.
• subscription_id, promotion_id and gift_code_flags to remain undocumented at this time
• Updated before and after param descriptions for List Entitlements to be more explicit. Snowflake IDs are time-ordered.

Addressing docs for SKUs (#6468)

The flags field is mentioned in a bunch of places in the SKU documentation but it's not documented.
Furthermore, the json includes a bunch more info that aren't present in the object structure documentation.

• Flags was added to documentation in Tweak documentation for premium apps (aka. application subscriptions) #6452
• Removed consumed as it is not usable by devs

For both models:

• The JSON examples DO contain fields not included in the table. Fields that can be used by devs today are documented in the tables with descriptions. Something we hope to address in the future but for now, rely on the defined fields.

[Lulalaby]

Looks good

[mkrasnitski]

Are the before and after parameters mutually exclusive in any way?

[Luc1412]

• Added deleted.

I talked to mason regarding this when implementing Rapptz/discord.py#9453. From what he told me, the deleted field got no relevance. (Might even not work or change for premium SKUs) And we should rely on ends_at not being refreshed.
So it actually got any value?

[appellation]

Entitlements can be deleted in some scenarios. This field should be documented so that apps can use it.

[Luc1412]

Entitlements can be deleted in some scenarios. This field should be documented so that apps can use it.

If Discord themselves manually delete it due to refunds/fraud for example. For normal expiry it won't be set True. However does it even will be available when it's deleted, since it also disappears when deleting a test entitlement.

If it's not true when it expires, it may be better to point it out, as it can be misleading.