Make "create_n_policies" script (#16517)

## Tool for testing policies-related features

When you just need a bunch of random policies:
<img width="1487" alt="Screenshot 2024-01-31 at 1 30 54 PM"
src="https://github.com/fleetdm/fleet/assets/61553566/77165bb9-8194-44e5-b57f-9e691de44785">

<img width="948" alt="Screenshot 2024-01-31 at 1 31 17 PM"
src="https://github.com/fleetdm/fleet/assets/61553566/ad72ae8c-926f-461f-8824-53b8ae0d4c2f">


- [x] Manual QA for all new/changed functionality

---------

Co-authored-by: Jacob Shandling <jacob@fleetdm.com>

tools/api/fleet/policies/create_n_policies

@@ -0,0 +1,34 @@
+#!/usr/bin/python3
+
+'''
+Create n new policies, where n is the integer first argument passed to the script.
+
+Assumes the script can see the `TOKEN` (API token) and `SERVER_URL` environment variables.
+'''
+
+import subprocess, os, sys, string, random
+
+POLICIES_ENDPOINT="/api/latest/fleet/policies"
+
+def main(n: int):
+  token, server_url = os.environ.get("TOKEN"), os.environ.get("SERVER_URL")
+  if not token or not server_url:
+    raise Exception("Make sure you have set TOKEN and SERVER_URL as environment variables.")
+  for i in range(n):
+      name='Policy ' + ''.join(random.choices(string.ascii_lowercase, k=5))
+      critical=random.choice(["true", "false"])
+      data = f'{{"name": "{name}", "query": "SELECT 1 FROM osquery_info;", "description": "Selects 1", "resolution": "Resolution steps", "platform": "{random.choice(["windows", "linux", "darwin"])}", "critical": {critical}}}'
+      process = subprocess.Popen(
+        ["curl", "-X", "POST", "-k", "-s", "-H", f"Authorization: Bearer {token}", f"{server_url}{POLICIES_ENDPOINT}", "-d", f"{data}", "--insecure"], stdout=subprocess.PIPE
+      )
+      (out, err) = process.communicate()
+      print(out, "\n")
+
+
+
+if __name__ == "__main__":
+    try:
+      n = int(sys.argv[1])
+    except:
+      raise Exception("Enter the number of policies to create as a single integer argument.")
+    main(n)