Related to T2964

It has a major regression for timestamps:
https://github.com/msgpack/msgpack-python/issues/451

1. for consistency with the serializers in swh.core
2. it's not clear to me that we ever needed that (it was added in
   64cd01fc with no rational)
3. it messes with swh-search reading from the journal and expecting
   JSON-like data.

to have support for datetime/timestamp.

previous revision did in fact killed the dependencu on swh.core but did
not update the rquirements file accordingly.

The encoding of datetime objects is done using msgpack extension types
(instead of former b'swhtype" custom types).

Note that this imply that the timezone of the encoded datime is "lost in
translation": the resulting datetime will be a (tz-aware) UTC datetime
object.

Support for decoding these later is however provided for backward
compatbility.

Also make the serialization code of the journal independant from
swh.core.api.serializer.

This later move aims at making the msgpack serialization process of the
journal to be specified (and predictable). The code from swh.core is
dedicated at RPC and can thus do much more "custom types" than what is
needed for the journal. So by not using the serialization code from the
swh.core pakage, we make sure we do not inadvertently encode unspecified
objects in the journal.

Related to T2834

So that errors in unique_key() are caught by tests using the in-mem writer.

The indexer-storage will use this.

Instead of being a method of KafkaJournalWriter.

This will allow using JournalWriters for values that aren't model objects.

The old attribute was deprecated in swh.model 0.7.2

We don't use @overload in this module anymore.

swh.journal.writer.kafka imports it from serializers.

Related to T2610

Related to T2610

kafka_to_value didn't recursively convert to tuples, so they were
of type Tuple[List[bytes], ...] instead of Tuple[Tuple[bytes, bytes], ...]

Following swh.model 0.6.6 bump

Related to T2501

Required, to have the 'object_type' attribute on metadata object classes.

TEST_OBJECT_DICTS isn't used in any other package.

instead of dicts.

This is needed because we are beginning to use converters in swh.model,
so the dict used as input is not guaranteed to be the exact same one
as the one retrieved from the journal.

For this, we need to include the data attribute in journal_data's
Content objects so we have "true" Content objects in tests.
Which then requires a few adjustments in journal tests because the
Content's data is never sent to the journal.

Related to T2310

for the sake of correctness.

As this is no longer compatible with latest model, that code makes the storage
builds fail.

This sets the fields status, metadata and snapshot from the origin-visit
entries to None (as per the recent model change D3340)

This pulls the creation of origin-visit-status with almost the same
origin-visit entries as before. The origin-visit-status dates are slightly
larger than the origin-visit ones so we are able to reflect the reality of
operations (first creation of origin visits, then creation of
origin-visit-status associated to that origin-visit).

Related to T2310

This metadata field is kind of deprecated, and having values there
may cause failures in tests using a Postgresql backend storage.

Prior to this commit, when error happened during testing, this would cascade
into another error ("unhashable type dict" for example). In effect, preventing
to actually understand correctly what went wrong in the first place.

This commit fixes it.

Related to T2310

This is also preparatory work for D3241

Improve the coverage of the test set provided in journal_data, namely
add directories, snapshots and skipped contents.

This requires to adapt a bit the function assert_all_objects_consumed() from
pytest_plugin, because we want to be able to handle anonymizable objects
specifically. So for now, simply add an 'exclude' argument.

It also needs the kafka_to_value serializer function to ensure tuples are
used instead of lists.

in which parents are expected to be a tuple instead of a list.

even if this class is meant to be removed soon, this fix is needed to
make swh-storage tests pass ok for now.

The idea is to publish on a "public" prefix anonymized objects and have a
priviledged prefix for non-anonymized ones. Every model object which
".anonymize()" method returns a(n anonymized) model object will be sent
to both channels (anonymized version on the regular channel, and
original version on the privileged channel).

Currently only Release and Revision objects are anonymizable.

For anonymizable objects:

- regular (non-anonymized) objects are sent to the topic

  "{prefix}_privileged.{object_type}"

- anonymized version of these objects are sent to

  "{prefix}.{object_type}"

On the client side, a new boolean "privileged" config parameter is used to
select privileged topics if vivible on the Kafka broker at subscrition time.