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

It's used in multiple module tests now.

Related to T2987

Related to T2987

Note that the current implementation will start back the new visit from the last
next_page link seen (that's what is stored in the lister state to avoid computing back
the url). This means that this page will be seen at least 2 times, on the first visit
and on the next. This should not pose any problems as the listing is idempotent.

Related to T2987

Related to T2987

Related to T2987

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

As before, the lister can be run in full or incremental mode.
When using incremental mode, only new and modified packages will
be returned since the last incremental listing process.
Otherwise, all packages will be listed in lexicographical order.

One major improvement to be noted, latest package update date
is now retrieved when available and sent to scheduler database.

Closes T2972

The new lister has only full listing capability.
It scrapes pypi.org list of packages.
Rate-limiting was not encountered but is handled generically.