tests: verify `SetConstIterator` works in Python bindings

The problem is that the assignment statement in Python never copies
objects, this means that when we get a reference (returned by
`SetConstIterator::operator*()` to internal query object it is valid
only as long as the query lives.

This means that without additional changes this is a problem for
`RepoQuery`, `GroupQuery` and `EnvironmentQuery`. For me it doesn't
crash with `RepoQuery` (probably due to different memory layout) but it
is caught when run with Sanitizers or valgrind.

To verify with valgrind:
from `dnf5/test/python3/libdnf5` do
`$ PROJECT_BINARY_DIR=../../../build \
PROJECT_SOURCE_DIR=../../../ valgrind python3.13 -m unittest \
repo.test_repo_query.TestRepoQuery.test_repo_query`

This behavior is unexpected in Python, it should manage livetimes
automatically.

test/python3/libdnf5/comps/test_group.py

@@ -45,3 +45,22 @@ class TestGroup(base_test_case.BaseTestCase):
         query = libdnf5.comps.GroupQuery(self.base)
         core_group = next(iter(query))
         self.assertEqual(5, len(core_group.get_packages()))
+
+    def test_group_when_query_out_of_scope(self):
+        self.add_repo_repomd("repomd-comps-core")
+
+        def get_group(base):
+            query = libdnf5.comps.GroupQuery(base)
+            return next(iter(query))
+
+        self.assertEqual(5, len(get_group(self.base).get_packages()))
+
+    def test_iterating_over_inline_query(self):
+        self.add_repo_repomd("repomd-comps-core", False)
+        self.add_repo_repomd("repomd-comps-standard")
+
+        ids = []
+        for grp in sorted(libdnf5.comps.GroupQuery(self.base), key=lambda x: int(x.get_order_int())):
+            ids.append(grp.get_groupid())
+
+        self.assertEqual(['core', 'standard'], ids)

test/python3/libdnf5/repo/test_repo_query.py

@@ -70,3 +70,13 @@ class TestRepoQuery(base_test_case.BaseTestCase):
             result.add(repo.get_id())
         self.assertEqual(
             result, {"repo1", "repo2", "repo1_updates", "repo2_updates"})
+
+        # Tests repo objects after query goes out of scope
+        repos_list = []
+        for repo in libdnf5.repo.RepoQuery(self.base):
+            repos_list.append(repo)
+        result = set()
+        for repo in repos_list:
+            result.add(repo.get_id())
+        self.assertEqual(
+            result, {"repo1", "repo2", "repo1_updates", "repo2_updates"})