The previous implementation was generating tasks for a non implemented
Packagist loader.

The new implementation extracts source repository URL, VCS type and
last update date for each package referenced by Packagist and send
those info to the scheduler.

Packages metadata are retrieved using Packagist API endpoints whose
responses are served from static files, which are guaranteed to be
efficient on the Packagist side (no dymamic queries).
Furthermore, subsequent listing will send the "If-Modified-Since" HTTP
header to only retrieve packages metadata updated since the previous
listing operation in order to save bandwidth and return only origins
which might have new released versions.

Closes T2991

UTC timezone settings can be obtained from the datetime.timezone
module from Python standard library so remove dependency on external
pytz module.

Ensure the behavior is the same when a base url is provided or not

Related to T3013#57810

Listers like github and bitbucket should not be impacted as they already list 1000
records per page.

This adds a second behavior to the cgit lister to actually compute origin urls instead
of parsing them out of another http request on git detailed page.

This new behavior is expected to be the default behavior.

The old behavior is kept for now and is expected to be used as fallback if too much
false negatives are returned.

Related to T2999

ISO functionalities port of the stateless GNU lister to the new
swh.lister.pattern.Lister API.

Closes T2990

This generates an error due to the datetime type field, so manually build
the dict instead.

Related to T3003#57551

launchpadlib can list the last modified repository twice so ensure to yield
a single ListedOrigin model for that special case.

Related to T3003#57551

In effect, it just allows to add credentials to cgit, cran and pypi listers.

This fixes instances of error [1]

[1] https://sentry.softwareheritage.org/share/issue/a5fb50f8e43e4b328c4917771576c6b0/

Related to T2998

An exception is raised when registering task types in scheduler database otherwise.

As origins is a generator, the previous behavior would try to consume the overall
generator to send the records.

This groups and sends batch of 100 origins to the scheduler for writing.

Related to T3003

Port launchpad lister to the swh.lister.pattern.Lister API.

Last update date of each listed git repositories is now sent to the scheduler.

The lister can work in incremental mode, only modified repositories since
the last listing operation will be returned in that case.

Closes T2992

In effect, it just allows to add credentials to cgit, cran and pypi listers.

This fixes instances of error [1]

[1] https://sentry.softwareheritage.org/share/issue/2c35a9f129cf4982a2dd003a232d507a/

Related to T2998

This fixes the master build [1]

[1] https://jenkins.softwareheritage.org/job/DLS/job/tests/1210/console

while allowing legacy lister to still run (with --legacy)

Drop launchpad lister from the lister to check, its test setup is more involved than the
other listers. As its setup is not done in that test, it's actually connecting
anonymously to the launchpad server. So remove such lister from the test.

This should also fix the debian build which refuses such access [1]

[1] https://jenkins.softwareheritage.org/job/debian/job/packages/job/DLS/job/gbp-buildpackage/97/console

This current test was failing in a debian chroot with connection error.

The listers depending on it got ported to the new lister api.

Plus that instruction is not correct in most recent requests_mock version (failing the
debian build)

Related to T2988

Related to T2988

Port debian lister to `swh.lister.pattern.Lister` API.

The new implementation will produce one instance of ListedOrigin model
per package, notably containing the set of parameters expected by the
debian loader.

The lister is also stateful, meaning only new packages and those with
new found versions since the last listing will be returned.

Closes T2979

All the fixtures declared in them are not used anymore in the
tests of the listers ported to the new Lister API.

The previous pagination implementation has a hard-coded limit server side [1]

[1]

```
{"error":"Offset pagination has a maximum allowed offset of 50000 for requests that return objects of type Project. Remaining records can be retrieved using keyset pagination."}
```

Related to T2994

R package last update date can be found in the "Packaged" field of
package info returned by tools::CRAN_package_db().

So retrieve it and parse it as a datetime to provide as last_update
parameter value in ListedOrigin model.

Closes T2989

Related to T2989

Related to T2987

Related to T2984

The PaginatedListedOriginList model has been updated in
rDSCHb93aa5be2c2d5dc2130e1027698f3e1255052d8d and the origins
field has been renamed to results.

The lister is stateless and has full listing capability.
It can request the Gitea API using HTTP token authentication.
Rate-limiting was not encountered but is handled generically.
Added support for getting repo last update date through API.

Related to T2987

Related to T2984

Use random credentials from the list in configuration and improve related
logging messages.

Related to T2987