Apply policies for normal and pipeline mode (#3818)

* Added poilcy resolution method

* Moved main command proceessing on top

* Fixed return type and keyless detection

* Added Dynamic and Static policies

* Added coverage for policy resolvers

* Applied request policies

* Removed all policies except search (phase 1)

* Policy applied for normal and pipeline mode

* Added assertion with core command

* Applied comments

* Renamed method

Author: vladvildanov

redis/_parsers/commands.py

@@ -11,10 +11,12 @@
 class RequestPolicy(Enum):
     ALL_NODES = 'all_nodes'
     ALL_SHARDS = 'all_shards'
+    ALL_REPLICAS = 'all_replicas'
     MULTI_SHARD = 'multi_shard'
     SPECIAL = 'special'
     DEFAULT_KEYLESS = 'default_keyless'
     DEFAULT_KEYED = 'default_keyed'
+    DEFAULT_NODE = 'default_node'
 
 class ResponsePolicy(Enum):
     ONE_SUCCEEDED = 'one_succeeded'
@@ -162,7 +164,9 @@ def get_keys(self, redis_conn, *args):
                     for subcmd in command["subcommands"]:
                         if str_if_bytes(subcmd[0]) == subcmd_name:
                             command = self.parse_subcommand(subcmd)
-                            is_subcmd = True
+
+                            if command['first_key_pos'] > 0:
+                                is_subcmd = True
 
                 # The command doesn't have keys in it
                 if not is_subcmd: