Don't raise errors when using datetime objects in as_datetime Jinja function/filter (#109062)

* add support for datetime objects to as_datetime

* change import of datetime.date

---------

Co-authored-by: Erik Montnemery <erik@montnemery.com>

homeassistant/helpers/template.py

@@ -9,7 +9,7 @@ import collections.abc
 from collections.abc import Callable, Generator, Iterable
 from contextlib import AbstractContextManager, suppress
 from contextvars import ContextVar
-from datetime import datetime, timedelta
+from datetime import date, datetime, time, timedelta
 from functools import cache, lru_cache, partial, wraps
 import json
 import logging
@@ -2001,12 +2001,12 @@ def square_root(value, default=_SENTINEL):
 def timestamp_custom(value, date_format=DATE_STR_FORMAT, local=True, default=_SENTINEL):
     """Filter to convert given timestamp to format."""
     try:
-        date = dt_util.utc_from_timestamp(value)
+        result = dt_util.utc_from_timestamp(value)
 
         if local:
-            date = dt_util.as_local(date)
+            result = dt_util.as_local(result)
 
-        return date.strftime(date_format)
+        return result.strftime(date_format)
     except (ValueError, TypeError):
         # If timestamp can't be converted
         if default is _SENTINEL:
@@ -2048,6 +2048,12 @@ def forgiving_as_timestamp(value, default=_SENTINEL):
 
 def as_datetime(value: Any, default: Any = _SENTINEL) -> Any:
     """Filter and to convert a time string or UNIX timestamp to datetime object."""
+    # Return datetime.datetime object without changes
+    if type(value) is datetime:
+        return value
+    # Add midnight to datetime.date object
+    if type(value) is date:
+        return datetime.combine(value, time(0, 0, 0))
     try:
         # Check for a valid UNIX timestamp string, int or float
         timestamp = float(value)