Hook up listers implemented with the new pattern to the CLI

We stop depending on the ListerBase implementation. The main hoop we're jumping
through is the config override mechanism in swh.lister.get_lister, as it's
really specifc to the ListerBase `override_config` argument, which is dropped in
pattern.Lister (in favor of explicit arguments at lister instantiation).

We implement a small shim in swh.lister.pattern.Lister to give
backwards-compatibility for the new pattern to get_lister.

This generic configuration override mechanism will probably be completely
removed when the configuration mechanism is reworked. We'll see.

swh/lister/tests/test_cli.py

@@ -6,7 +6,6 @@
 import pytest
 
 from swh.lister.cli import SUPPORTED_LISTERS, get_lister
-from swh.lister.core.lister_base import ListerBase
 
 from .test_utils import init_db
 
@@ -19,17 +18,16 @@ def test_get_lister_wrong_input():
     assert "Invalid lister" in str(e.value)
 
 
-def test_get_lister():
+def test_get_lister(swh_scheduler_config):
     """Instantiating a supported lister should be ok
 
     """
     db_url = init_db().url()
-    # exclude listers because they need special instantiation treatment unrelated to
-    # this test (launchpad: network mock, gnu: scheduler load task)
-    listers_to_instantiate = set(SUPPORTED_LISTERS) - {"launchpad", "gnu"}
-    for lister_name in listers_to_instantiate:
-        lst = get_lister(lister_name, db_url)
-        assert isinstance(lst, ListerBase)
+    for lister_name in SUPPORTED_LISTERS:
+        lst = get_lister(
+            lister_name, db_url, scheduler={"cls": "local", **swh_scheduler_config}
+        )
+        assert hasattr(lst, "run")
 
 
 def test_get_lister_override():
@@ -47,9 +45,7 @@ def test_get_lister_override():
     # check the override ends up defined in the lister
     for lister_name, url in listers.items():
         lst = get_lister(
-            lister_name,
-            db_url,
-            **{"url": url, "priority": "high", "policy": "oneshot",},
+            lister_name, db_url, url=url, priority="high", policy="oneshot"
         )
 
         assert lst.url == url