Linode: Mark 'name' as required. Fixes #29785 (#44699)

* Mark 'name' parameter as required.

Closes https://github.com/ansible/ansible/issues/29785.

* Add the `linode-python` dependency for unit tests.

* Add unit test for linode name parameter.

* Add note about where to find required arguments.

Closes https://github.com/ansible/ansible/issues/44696.

test/units/modules/cloud/linode/test_linode.py

@@ -0,0 +1,15 @@
+from __future__ import (absolute_import, division, print_function)
+
+import pytest
+
+from ansible.modules.cloud.linode import linode
+from units.modules.utils import set_module_args
+
+if not linode.HAS_LINODE:
+    pytestmark = pytest.mark.skip('test_linode.py requires the `linode-python` module')
+
+
+def test_name_is_a_required_parameter(api_key, auth):
+    with pytest.raises(SystemExit):
+        set_module_args({})
+        linode.main()