Allow to mark files in a PR as viewed (#19007)

Users can now mark files in PRs as viewed, resulting in them not being shown again by default when they reopen the PR again.

routers/web/web.go

@@ -849,6 +849,7 @@ func RegisterRoutes(m *web.Route) {
 				m.Post("/deadline", bindIgnErr(structs.EditDeadlineOption{}), repo.UpdateIssueDeadline)
 				m.Post("/watch", repo.IssueWatch)
 				m.Post("/ref", repo.UpdateIssueRef)
+				m.Post("/viewed-files", repo.UpdateViewedFiles)
 				m.Group("/dependency", func() {
 					m.Post("/add", repo.AddDependency)
 					m.Post("/delete", repo.RemoveDependency)