[dashboards] Add support for dashboard list API v2

[jbenais]

• Add DashboardList.v2.get_items, DashboardList.v2.add_items, DashboardList.v2.update_items and DashboardList.v2.delete_items API calls

[gzussa]

Why did we choose to have v2 as a sub variable within DashboardList? Would it be better to have a DashboardListV2 such a way we can do api.DashboardListV2 directly? Also, did we consider having something like api.v2.DashboardList?

[jbenais]

Why did we choose to have v2 as a sub variable within DashboardList? Would it be better to have a DashboardListV2 such a way we can do api.DashboardListV2 directly?

Adding a DashboardListV2 class means that we would have to do the same for all other classes that would need to be versioned and it can become very messy at some point. We also wanted to keep the name DashboardList because we want users to use the latest version of our API at the end. Having DashboardListV2 could let users think that they can use either DashboardList or DashboardListV2, which we don't want. This is why we wanted to implement a solution that would allow, in the future, to manage API updates in a simple way. With this approach, you can specify your endpoint version easily.

Also, did we consider having something like api.v2.DashboardList?

In general, when it comes to versioning, adding the prefix 'v2' after 'api' means that the whole api has been updated to another version, which is not the case here since only 4 endpoints have been updated. We have therefore chosen to place 'v2' after DashboardList to avoid any confusion and also because it seems clear enough for the users.