<!--

Welcome to Apache Airflow!  For a smooth issue process, try to answer the following questions.
Don't worry if they're not all applicable; just try to include what you can :-)

If you need to include code snippets or logs, please put them in fenced code
blocks.  If they're super-long, please use the details tag like
<details><summary>super-long log</summary> lots of stuff </details>

Please delete these comment blocks before submitting the issue.

-->

**Description**

<!-- A short description of your feature -->

Make `MongoToS3Operator` `mongo_collection` parameter templated.

**Use case / motivation**

<!-- What do you want to happen?

Rather than telling us how you might implement this solution, try to take a
step back and describe what you are trying to achieve.

-->

This would allow for passing a templated mongo collection from other tasks, such as a mongo collection used as data destination by using `S3Hook`. For instance, we could use templated mongo collection to write data for different dates in different collections by using: `mycollection.{{ ds_nodash }}`.

**Are you willing to submit a PR?**

<!--- We accept contributions! -->

Yes.

**Related Issues**

<!-- Is there currently another issue associated with this? -->

N/A

tests/providers/amazon/aws/transfers/test_mongo_to_s3.py
#
#
#
import unittest
from unittest import mock
from airflow.models import TaskInstance
from airflow.models.dag import DAG
from airflow.providers.amazon.aws.transfers.mongo_to_s3 import MongoToS3Operator
from airflow.utils import timezone
TASK_ID = 'test_mongo_to_s3_operator'
MONGO_CONN_ID = 'default_mongo'
S3_CONN_ID = 'default_s3'
MONGO_COLLECTION = 'example_collection'
MONGO_QUERY = {"$lt": "{{ ts + 'Z' }}"}
S3_BUCKET = 'example_bucket'
S3_KEY = 'example_key'
DEFAULT_DATE = timezone.datetime(2017, 1, 1)
MOCK_MONGO_RETURN = [
    {'example_return_key_1': 'example_return_value_1'},
    {'example_return_key_2': 'example_return_value_2'},
]
class TestMongoToS3Operator(unittest.TestCase):