move generic atd wrappers to separate file

Author: yasunariw

lib/common.atd

@@ -0,0 +1,3 @@
+type 'v map_as_object =
+  (string * 'v) list <json repr="object">
+    wrap <ocaml module="Common.StringMap" t="'v Common.StringMap.t">

lib/dune

@@ -6,6 +6,18 @@
  (preprocess
   (pps lwt_ppx)))
 
+(rule
+ (targets common_t.ml common_t.mli)
+ (deps common.atd)
+ (action
+  (run atdgen -t %{deps})))
+
+(rule
+ (targets common_j.ml common_j.mli)
+ (deps common.atd)
+ (action
+  (run atdgen -j -j-std %{deps})))
+
 (rule
  (targets github_t.ml github_t.mli)
  (deps github.atd)

lib/slack.atd

@@ -1,4 +1,4 @@
-type 'v map_as_object <ocaml from="State"> = abstract
+type 'v map_as_object <ocaml from="Common"> = abstract
 
 type message_field = {
   ?title: string nullable;

lib/state.atd

@@ -1,8 +1,5 @@
 type status_state <ocaml from="Github"> = abstract
-
-type 'v map_as_object =
-  (string * 'v) list <json repr="object">
-    wrap <ocaml module="Common.StringMap" t="'v Common.StringMap.t">
+type 'v map_as_object <ocaml from="Common"> = abstract
 
 (* A map from branch names to build statuses *)
 type branch_statuses = status_state map_as_object