[MM-38239 & MM-39788] Recent files causing crash (#18942)

* wip

* adding tests for new endpoint

* tool updates

* new function for getting postsByIds

* fixing test

* adding limit of 1000 to post query

* fixing PR comments

* fixing permission logic

Co-authored-by: Collin <collineng@gmail.com>
Co-authored-by: Collin Eng <eng.engineereng@gmail.com>
Co-authored-by: Benjamin Cooke <benjamincooke@Benjamins-MacBook-Pro.local>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>
Co-authored-by: Benjamin Cooke <benjamincooke@Benjamins-MBP.ht.home>

store/sqlstore/post_store.go

@@ -1978,6 +1978,9 @@ func (s *SqlPostStore) GetPostsByIds(postIds []string) ([]*model.Post, error) {
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to find Posts")
 	}
+	if len(posts) == 0 {
+		return nil, store.NewErrNotFound("Post", fmt.Sprintf("postIds=%v", postIds))
+	}
 	return posts, nil
 }