Refactor to split s3_client.py into multiple files

Separated s3_client.py into 3 files - for logos, CSV files and the MOU.
This helps to keep things clearer now that we need to add lots more logo
functions for letters.

app/s3_client/s3_csv_client.py

@@ -0,0 +1,57 @@
+import uuid
+
+import botocore
+from flask import current_app
+from notifications_utils.s3 import s3upload as utils_s3upload
+
+from app.s3_client.s3_logo_client import get_s3_object
+
+FILE_LOCATION_STRUCTURE = 'service-{}-notify/{}.csv'
+
+
+def get_csv_location(service_id, upload_id):
+    return (
+        current_app.config['CSV_UPLOAD_BUCKET_NAME'],
+        FILE_LOCATION_STRUCTURE.format(service_id, upload_id),
+    )
+
+
+def get_csv_upload(service_id, upload_id):
+    return get_s3_object(*get_csv_location(service_id, upload_id))
+
+
+def s3upload(service_id, filedata, region):
+    upload_id = str(uuid.uuid4())
+    bucket_name, file_location = get_csv_location(service_id, upload_id)
+    utils_s3upload(
+        filedata=filedata['data'],
+        region=region,
+        bucket_name=bucket_name,
+        file_location=file_location,
+    )
+    return upload_id
+
+
+def s3download(service_id, upload_id):
+    contents = ''
+    try:
+        key = get_csv_upload(service_id, upload_id)
+        contents = key.get()['Body'].read().decode('utf-8')
+    except botocore.exceptions.ClientError as e:
+        current_app.logger.error("Unable to download s3 file {}".format(
+            FILE_LOCATION_STRUCTURE.format(service_id, upload_id)))
+        raise e
+    return contents
+
+
+def set_metadata_on_csv_upload(service_id, upload_id, **kwargs):
+    get_csv_upload(
+        service_id, upload_id
+    ).copy_from(
+        CopySource='{}/{}'.format(*get_csv_location(service_id, upload_id)),
+        ServerSideEncryption='AES256',
+        Metadata={
+            key: str(value) for key, value in kwargs.items()
+        },
+        MetadataDirective='REPLACE',
+    )