Add task to fetch and store codespaces metrics

As the codespaces data will change over time and deleted codespaces
will disappear from the API, we do not drop and recreate the table
each time the task is run as per the other tasks. Instead, calling
the upsert() method ensures the table exists then merges the new
data with the existing.

Conversion method added to metrics.py is not a metric in the usual
sense of the word, but instead renames some fields to match the
database schema. This is neccesary due to different naming conventions
in the domain dataclasses and database tables.

metrics/github/metrics.py

@@ -75,3 +75,16 @@ def convert_issue_counts_to_metrics(counts):
             }
         )
     return metrics
+
+
+def convert_codespaces_to_dicts(codespaces):
+    return [
+        {
+            "organisation": c.org,
+            "repo": c.repo_name,
+            "user": c.user,
+            "created_at": c.created_at,
+            "last_used_at": c.last_used_at,
+        }
+        for c in codespaces
+    ]

metrics/tasks/codespaces.py

@@ -0,0 +1,24 @@
+import sys
+
+import structlog
+
+import metrics.github.github as github
+from metrics.github.metrics import convert_codespaces_to_dicts
+from metrics.timescaledb import db, tables
+
+
+log = structlog.get_logger()
+
+
+def main():
+    log.info("Getting codespaces")
+    codespaces = github.codespaces(org="opensafely")
+    log.info(f"Got {len(codespaces)} codespaces")
+
+    log.info("Writing data")
+    db.upsert(tables.GitHubCodespaces, convert_codespaces_to_dicts(codespaces))
+    log.info("Written data")
+
+
+if __name__ == "__main__":
+    sys.exit(main())