Merged PR 291: #2357 - Allow empty nodes, links, and agents arrays in config file

## Summary
Allowed the config to not have nodes, links and agents and still be parsed

## Test process
Tested with config file that doesn't have any simulation key/value pair

## Checklist
- [X] PR is linked to a **work item**
- [X] **acceptance criteria** of linked ticket are met
- [X] performed **self-review** of the code
- [X] written **tests** for any new functionality added with this PR
- [ ] updated the **documentation** if this PR changes or adds functionality
- [ ] written/updated **design docs** if this PR implements new functionality
- [ ] updated the **change log**
- [X] ran **pre-commit** checks for code style
- [ ] attended to any **TO-DOs** left in the code

#2357 - Allowed the config to not have nodes, links and agents and still be parsed

Related work items: #2357

tests/assets/configs/no_nodes_links_agents_network.yaml

@@ -0,0 +1,31 @@
+training_config:
+  rl_framework: SB3
+  rl_algorithm: PPO
+  seed: 333
+  n_learn_episodes: 1
+  n_eval_episodes: 5
+  max_steps_per_episode: 128
+  deterministic_eval: false
+  n_agents: 1
+  agent_references:
+    - defender
+
+io_settings:
+  save_checkpoints: true
+  checkpoint_interval: 5
+  save_step_metadata: false
+  save_pcap_logs: true
+  save_sys_logs: true
+
+
+game:
+  max_episode_length: 256
+  ports:
+    - ARP
+    - DNS
+    - HTTP
+    - POSTGRES_SERVER
+  protocols:
+    - ICMP
+    - TCP
+    - UDP

tests/integration_tests/configuration_file_parsing/test_no_nodes_links_agents_config.py

@@ -0,0 +1,19 @@
+import yaml
+
+from primaite.game.game import PrimaiteGame
+from tests import TEST_ASSETS_ROOT
+
+CONFIG_FILE = TEST_ASSETS_ROOT / "configs" / "no_nodes_links_agents_network.yaml"
+
+
+def test_no_nodes_links_agents_config():
+    """Tests PrimaiteGame can be created from config file where there are no nodes, links, agents in the config file."""
+    with open(CONFIG_FILE, "r") as f:
+        cfg = yaml.safe_load(f)
+
+    game = PrimaiteGame.from_config(cfg)
+
+    network = game.simulation.network
+
+    assert len(network.nodes) == 0
+    assert len(network.links) == 0