graph-validator-post: built initial graph-validator for group feed

pkg/arvo/mar/graph/validator/post.hoon

@@ -0,0 +1,30 @@
+/-  *post, met=metadata-store
+|_  i=indexed-post
+++  grow
+  |%
+  ++  noun  i
+  ++  graph-permissions-add
+    |=  vip=vip-metadata:met
+    ?:  ?=([@ ~] index.p.i)
+      [%yes %yes %no]
+    [%yes %yes ?:(?=(%reader-comments vip) %yes %no)]
+  ::
+  ++  graph-permissions-remove
+    |=  vip=vip-metadata:met
+    [%yes %self %self]
+  ::  +notification-kind: no notifications for now
+  ::
+  ++  notification-kind  ~
+  --
+++  grab
+  |%
+  :: +noun: validate post
+  :: 
+  ++  noun
+    |=  p=*
+    =/  ip  ;;(indexed-post p)
+    ?>  ?=(^ contents.p.ip)
+  --
+::
+++  grad  %noun
+--

pkg/arvo/mar/graph/validator/publish.hoon

@@ -33,7 +33,7 @@
   --
 ++  grab
   |%
-  :: +noun: validate publish post
+  :: +noun: validate publish note
   :: 
   ++  noun
     |=  p=*