feat: set default current-date for collection_from_items script TDE-1298

 (#1196)

### Motivation

As a basemaps developer, I do not want to set many mandatory CLI
arguments.

### Modifications

Added the current date / time as a semi-sane default for the
--current-date command line argument

### Verification

pytest

scripts/collection_from_items.py

@@ -2,6 +2,7 @@
 import json
 import os
 from argparse import Namespace
+from datetime import datetime, timezone
 from typing import TYPE_CHECKING, List
 
 import shapely.geometry
@@ -10,7 +11,7 @@
 from linz_logger import get_log
 
 from scripts.cli.cli_helper import coalesce_multi_single, str_to_gsd
-from scripts.datetimes import parse_rfc_3339_datetime
+from scripts.datetimes import RFC_3339_DATETIME_FORMAT, parse_rfc_3339_datetime
 from scripts.files.files_helper import SUFFIX_FOOTPRINT, SUFFIX_JSON
 from scripts.files.fs_s3 import bucket_name_from_path, get_object_parallel_multithreading, list_files_in_uri
 from scripts.logging.time_helper import time_in_ms
@@ -114,10 +115,11 @@ def parse_args(args: List[str] | None) -> Namespace:
         "--current-datetime",
         dest="current_datetime",
         help=(
-            "The datetime that is used as current datetime in the metadata. "
+            "The datetime to be used as current datetime in the metadata. "
             "Format: RFC 3339 UTC datetime, `YYYY-MM-DDThh:mm:ssZ`."
         ),
-        required=True,
+        required=False,
+        default=datetime.now(timezone.utc).strftime(RFC_3339_DATETIME_FORMAT),
     )
 
     return parser.parse_args(args)

scripts/tests/collection_from_items_test.py

@@ -70,8 +70,6 @@ def test_should_create_collection_file(item: ImageryItem, fake_linz_slug: str) -
         "Placeholder",
         "--concurrency",
         "25",
-        "--current-datetime",
-        any_epoch_datetime_string(),
         "--linz-slug",
         fake_linz_slug,
     ]