Add get_output_model_name_string() (#220)

Description
- *Category*: feature
- *JIRA issue*:  [MIC-3229](https://jira.ihme.washington.edu/browse/MIC-3229) and [MIC-3091](https://jira.ihme.washington.edu/browse/MIC-3091)

Changes:
- Add `get_output_model_name_string()` to be a standard way for both `psimulate run` and `simulate run` to create the same results paths.
- If an artifact is provided at the CLI, use the location there, if not, check the model specification YAML for an artifact and use its location. If there is no artifact (valid use case!), use the stem of the model specification filename.

Testing
Ran this VCT and Vivarium against IV Iron with an artifact provided only in the YAML and only at the command and @aflaxman's WA DOH staffing repo, which does not have an artifact and motivated one of these JIRA tickets. In each case, the correct artifact (if any) and results path location were as expected (`"south_asia"` in the former case and `"staffing"` in the latter, from `staffing.yaml`

src/vivarium/interface/cli.py

@@ -106,7 +106,7 @@ def run(
     configure_logging_to_terminal(verbose)
 
     start = time()
-    results_root = get_output_root(results_directory, model_specification)
+    results_root = get_output_root(results_directory, model_specification, artifact_path)
     results_root.mkdir(parents=True, exist_ok=False)
 
     configure_logging_to_file(results_root)

src/vivarium/interface/utilities.py

@@ -11,7 +11,9 @@
 import sys
 from datetime import datetime
 from pathlib import Path
+from typing import Union
 
+import yaml
 from loguru import logger
 
 from vivarium.exceptions import VivariumError
@@ -105,9 +107,43 @@ def wrapped_method(*args, **kwargs):
     return method_wrapper
 
 
-def get_output_root(results_directory, model_specification_file):
+def get_output_model_name_string(
+    artifact_path: Union[str, Path],
+    model_spec_path: Union[str, Path],
+) -> str:
+    """Find a good string to use as model name in output path creation.
+
+    Parameters
+    ----------
+    artifact_path
+        Path to the artifact file, if exists, else should be None
+    model_spec_path
+        Path to the model specification file. This must exist.
+
+    Returns
+    -------
+    str
+        A model name string for use in output labeling.
+    """
+    if artifact_path:
+        model_name = Path(artifact_path).stem
+    else:
+        with open(model_spec_path) as model_spec_file:
+            model_spec = yaml.safe_load(model_spec_file)
+        try:
+            model_name = Path(model_spec["configuration"]["input_data"]["artifact_path"]).stem
+        except KeyError:
+            model_name = Path(model_spec_path).stem
+    return model_name
+
+
+def get_output_root(
+    results_directory: Union[str, Path],
+    model_specification_file: Union[str, Path],
+    artifact_path: Union[str, Path],
+):
     launch_time = datetime.now().strftime("%Y_%m_%d_%H_%M_%S")
-    model_name = Path(model_specification_file).stem
+    model_name = get_output_model_name_string(artifact_path, model_specification_file)
     output_root = Path(results_directory + f"/{model_name}/{launch_time}")
     return output_root