port notes and project snippets

app/policies/note_policy.rb

+class NotePolicy < BasePolicy
+  def rules
+    delegate! @subject.project
+
+    return unless @user
+
+    if @subject.author == @user
+      can! :read_note
+      can! :update_note
+      can! :admin_note
+      can! :resolve_note
+    end
+
+    if @subject.for_merge_request? &&
+       @subject.noteable.author == @user
+      can! :resolve_note
+    end
+  end
+end

app/policies/project_snippet_policy.rb

+class ProjectSnippetPolicy < BasePolicy
+  def rules
+    can! :read_project_snippet if @subject.public?
+    return unless @user
+
+    if @user && @subject.author == @user || @user.admin?
+      can! :read_project_snippet
+      can! :update_project_snippet
+      can! :admin_project_snippet
+    end
+
+    if @subject.internal? && !@user.external?
+      can! :read_project_snippet
+    end
+
+    if @subject.private? && @subject.project.team.member?(@user)
+      can! :read_project_snippet
+    end
+  end
+end