Remove permission_allowed hook entirely, refs #2528

The permission_allowed hook has been fully replaced by permission_resources_sql.
This commit removes:
- hookspec definition from hookspecs.py
- 4 implementations from default_permissions.py
- implementations from test plugins (my_plugin.py, my_plugin_2.py)
- hook monitoring infrastructure from conftest.py
- references from fixtures.py
- Also fixes test_get_permission to use ds.get_action() instead of ds.get_permission()
- Removes 5th column (source_plugin) from PermissionSQL queries

This completes the migration to the SQL-based permission system.

tests/fixtures.py

@@ -44,7 +44,6 @@ EXPECTED_PLUGINS = [
             "forbidden",
             "homepage_actions",
             "menu_links",
-            "permission_allowed",
             "permission_resources_sql",
             "prepare_connection",
             "prepare_jinja2_environment",
@@ -74,7 +73,6 @@ EXPECTED_PLUGINS = [
             "extra_template_vars",
             "handle_exception",
             "menu_links",
-            "permission_allowed",
             "prepare_jinja2_environment",
             "register_routes",
             "render_cell",