Plonemeeting.restapi

----------------

- Adapted code as `Products.PloneMeeting.utils.add_wf_history_action` was moved
to `imio.history.utils.add_event_to_wf_history` and
`ToolPloneMeeting.getAdvicePortalTypes` and
`ToolPloneMeeting.getAdvicePortalTypeIds` were moved to utils.
[gbastien]

----------------

- Always include `type` info in result even when `include_base_data=false` as
it is used with `UidSearchGet.required_meta_type_id`.
[gbastien]

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- In `base.serialize_attendees`, do not use `UID` from serialized result as it
could not be there when using `include_base_data=false`.
[gbastien]

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- Added `attendees GET` on meeting and item and `attendee GET/PATCH`
on meeting and item. Added `extra_include=attendees` on meeting and item.
[gbastien]
- Manage `metadata_fields=internal_number`.
[gbastien]

------------------

- Fixed test isolation problem when tests executed together with `imio.pm.ws` tests.
[gbastien]

----------------

- Dropped support for `PloneMeeting 4.1.x`.
[gbastien]
- Add `config` to `extra_include` allowed parameters to return informations about the meeting config
[mpeeters]
- Ensure that `in_name_of` parameter is only handled once when `__children__` parameter is used
[mpeeters]
- Enforce usage of `UID` parameter only if `externalIdentifier` is not provided
[mpeeters]
- Added `test_restapi_add_item_manually_linked_items` to check that it is possible
to create items and use the `MeetingItem.manuallyLinkedItems` functionnality.
[gbastien]
- Adapted code as `MeetingConfig.useGroupsAsCategories` was removed.
Field `MeetingItem.category` is an optional field managed by
`MeetingConfig.usedItemAttributes` as any other optional fields now.
[gbastien]
- Add `date` by default to meeting informations.
[mpeeters]