[TASK] Stop supporting deprecated Portal functions

[alainncls]

When we introduced the "Modules V2" feature, some new functions were added to the Portal contract, to make sure we didn't break previous behaviours of already deployed Portals.

One way to ensure that newly deployed Portal contracts don’t support the deprecated functions anymore is the introduction of a new contract, AbstractPortalV2, that only supports the new set of functions; that approach would be similar to the introduction of AbstractModuleV2.

The original AbstractPortal contract should then be kept unaltered. Similar steps should be taken for concrete portals such as DefaultPortal, i.e., a new DefaultPortalV2 should inherit from AbstractPortalV2 and so on.