[raz] Improve RazGSConnection class for better code readability (#3617)

- Consolidating both RazGSConnection and SignedUrlGSConnection into one for better readability and improving docstrings.

desktop/core/src/desktop/lib/fs/gc/gsconnection.py

@@ -28,21 +28,28 @@
 LOG = logging.getLogger()
 
 
-class SignedUrlGSConnection(GSConnection):
+class RazGSConnection(GSConnection):
   """
-  Contact GS via a presigned Url of the resource hence not requiring any GS credentials.
+  Class asking a RAZ server presigned URLs for all the operations on GS resources hence not requiring any GS credentials.
+  Some operations can be denied depending on the privileges of the users in Ranger.
 
-  This is a client replacing the building of the Http Request of the GS resource via asking a third party providing for a presigned Urls.
+  This client replaces the building of the Http Request of the GS resource via asking RAZ for presigned URLs.
   The request information is then injected into the regular boto HTTPRequest as the format is the same. Raw calls via the requests
   lib would work but the unmarshalling back from XML to boto2 Python object is tedious.
 
-  The main logic consists in some light overrides in S3Connection#make_request() and AWSAuthConnection#make_request() so that we
+  Then fill-up the boto HttpRequest with the presigned Url data and lets boto executes the request as usual,
+  so that we get the XML unmarshalling for free.
+
+  Flow:
+    1. signed_url = self.get_signed_url(/bucket/dir/key)
+    2. request = http_request(signed_url)
+    3. return self._mexe(requests)
+  
+  The main logic consists in some light overrides in GSConnection#make_request() and AWSAuthConnection#make_request() so that we
   send an updated HTTPRequest.
-  https://github.com/boto/boto/blob/develop/boto/s3/connection.py
-  https://github.com/boto/boto/blob/develop/boto/connection.py
 
-  Example of a presigned GS Url declaring a `list bucket` call:
-  https://hue-gs-bucket.storage.googleapis.com/?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIA23E77ZX2HVY76YGL%2F20210505%2Fus-west-1%2Fs3%2Faws4_request&X-Amz-Date=20210505T171457Z&X-Amz-Expires=3600&X-Amz-SignedHeaders=host&X-Amz-Signature=994d0ec2ca19a00aa2925fe62cab0e727591b1951a8a47504b2b9124facbd6cf
+  https://github.com/boto/boto/blob/develop/boto/gs/connection.py
+  https://github.com/boto/boto/blob/develop/boto/connection.py
   """
   def __init__(self, username, gs_access_key_id=None, gs_secret_access_key=None,
                 is_secure=True, port=None, proxy=None, proxy_port=None,
@@ -56,7 +63,7 @@ def __init__(self, username, gs_access_key_id=None, gs_secret_access_key=None,
     # No auth handler with RAZ
     anon = RAZ.IS_ENABLED.get()
 
-    super(SignedUrlGSConnection, self).__init__(
+    super(GSConnection, self).__init__(
       gs_access_key_id=gs_access_key_id, gs_secret_access_key=gs_secret_access_key,
       is_secure=is_secure, port=port, proxy=proxy, proxy_port=proxy_port,
       proxy_user=proxy_user, proxy_pass=proxy_pass,
@@ -66,20 +73,6 @@ def __init__(self, username, gs_access_key_id=None, gs_secret_access_key=None,
     )
 
 
-class RazGSConnection(SignedUrlGSConnection):
-  """
-  Class asking a RAZ server presigned Urls for all the operations on GS resources.
-  Some operations can be denied depending on the privileges of the users in Ranger.
-
-  Then fill-up the boto HttpRequest with the presigned Url data and lets boto executes the request as usual,
-  so that we get the XML unmarshalling for free.
-
-  Flow:
-    1. signed_url = self.get_signed_url(/bucket/dir/key)
-    2. request = http_request(signed_url)
-    3. return self._mexe(requests)
-  """
-
   def make_request(self, method, bucket='', key='', headers=None, data='',
                     query_args=None, sender=None, override_num_retries=None,
                     retry_handler=None):