Merged PR 360: 2523 - Logging Rewards updates.

## Summary
This PR updates `PrimaiteGymEnv` and `PrimaiteRayMARLEnv` within `environment.py` to log reward values per step and per episode.
Corrects an import statement within `io.py` - removing the use of `src`.
Fixes an error within notebooks that saw them failing following a rename of `game_config` to `env_config`.

## Test process
 - Tests all continue to pass, and notebooks now run without error. This PR does not change any functionality, just adds some logging.
 - Searched for the catch-22 that would trip me up as part of this ticket. A 3 line change felt like too simple an implementation...

## Checklist
- [X] PR is linked to a **work item**
- [X] **acceptance criteria** of linked ticket are met
- [X] performed **self-review** of the code
- [ ] 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
- [X] updated the **change log**
- [X] ran **pre-commit** checks for code style
- [X] attended to any **TO-DOs** left in the code

Related work items: #2523

src/primaite/notebooks/Data-Manipulation-E2E-Demonstration.ipynb

@@ -404,7 +404,7 @@
     "    # don't flatten observations so that we can see what is going on\n",
     "    cfg['agents'][3]['agent_settings']['flatten_obs'] = False\n",
     "\n",
-    "env = PrimaiteGymEnv(game_config = cfg)\n",
+    "env = PrimaiteGymEnv(env_config = cfg)\n",
     "obs, info = env.reset()\n",
     "print('env created successfully')\n",
     "pprint(obs)"