lib.distros.Distro.install_*(): Add install_deps

The install methods of Distro inconsistently resolve dependencies or don't
depending on the descendant's implementation. Pin that more unambigously by
adding a new parameter install_deps, defaulting to True, to the following
methods of lib.Distro:

  _install_local_files()
  _install_urls()
  _install_urls_and_names()
  install()

The implementations in lib.distros.* make use of the new
lib.pm.*.install_packages() method introduced by the previous commit.

Add a unit test directory per Distro descendant.

Assisted-by: unsloth/Qwen3.8-27B-GGUF:Q4_K_M with pi.dev v1.4.0
Signed-off-by: Jan Lindemann <jan@janware.com>

test/unit/python/jw/pkg/lib/Distro/test.py

@@ -286,4 +286,23 @@ sde = SuseDistro(
 assert asyncio.run(sde.pkg_files()) == []
 assert '--queryformat' in cl.cmds[-1]
 
+# -- _install_local_files --
+
+# -- With dependency resolution, the files go to the package manager;
+#    DummyDistro._install() is a no-op
+asyncio.run(
+    d._install_local_files(['/a/jw-base-run-1.0.0-42.rpm'], False, install_deps = True)
+)
+
+# -- Without, the base implementation raises: there is no direct route
+try:
+    asyncio.run(
+        d._install_local_files(
+            ['/a/jw-base-run-1.0.0-42.rpm'], False, install_deps = False
+        )
+    )
+    assert False, 'Should have raised'
+except NotImplementedError:
+    pass
+
 print('All Distro tests passed')