fix: add missing `resource_type` callback implementations

apps/emqx_bridge_azure_blob_storage/src/emqx_bridge_azure_blob_storage_connector.erl

@@ -18,6 +18,7 @@
 %% `emqx_resource' API
 -export([
     callback_mode/0,
+    resource_type/0,
 
     on_start/2,
     on_stop/2,
@@ -148,6 +149,10 @@
 callback_mode() ->
     always_sync.
 
+-spec resource_type() -> atom().
+resource_type() ->
+    azure_blob_storage.
+
 -spec on_start(connector_resource_id(), connector_config()) ->
     {ok, connector_state()} | {error, _Reason}.
 on_start(_ConnResId, ConnConfig) ->

apps/emqx_bridge_couchbase/src/emqx_bridge_couchbase_connector.erl

@@ -15,6 +15,7 @@
 %% `emqx_resource' API
 -export([
     callback_mode/0,
+    resource_type/0,
 
     on_start/2,
     on_stop/2,
@@ -84,6 +85,10 @@
 callback_mode() ->
     always_sync.
 
+-spec resource_type() -> atom().
+resource_type() ->
+    couchbase.
+
 -spec on_start(connector_resource_id(), connector_config()) ->
     {ok, connector_state()} | {error, _Reason}.
 on_start(ConnResId, ConnConfig) ->

apps/emqx_cluster_link/src/emqx_cluster_link_mqtt.erl

@@ -19,6 +19,7 @@
 %% callbacks of behaviour emqx_resource
 -export([
     callback_mode/0,
+    resource_type/0,
     on_start/2,
     on_stop/2,
     on_query/3,
@@ -99,6 +100,10 @@ remove_msg_fwd_resource(ClusterName) ->
 
 callback_mode() -> async_if_possible.
 
+-spec resource_type() -> atom().
+resource_type() ->
+    cluster_link_mqtt.
+
 on_start(ResourceId, #{pool_size := PoolSize} = ClusterConf) ->
     PoolName = ResourceId,
     Options = [