chore: enable forcetypeassert linter, fix issues (#38804)

Enable [`forcetypeassert`](https://github.com/gostaticanalysis/forcetypeassert)
linter to prevent unchecked type assertions. ~650 issues fixed, most
fixes were clean, some use `setting.PanicInDevOrTesting`.

The only behaviour changes are where code would previously send a 500 error
or panic, a 4xx error is now emitted.

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/install/install.go

@@ -189,7 +189,7 @@ func SubmitInstall(ctx *context.Context) {
 
 	var err error
 
-	form := *web.GetForm(ctx).(*forms.InstallForm)
+	form := *web.GetForm[*forms.InstallForm](ctx)
 
 	// fix form values
 	if form.AppURL != "" && form.AppURL[len(form.AppURL)-1] != '/' {
@@ -524,7 +524,7 @@ func SubmitInstall(ctx *context.Context) {
 
 		// Now get the http.Server from this request and shut it down
 		// NB: This is not our hammerable graceful shutdown this is http.Server.Shutdown
-		srv := ctx.Value(http.ServerContextKey).(*http.Server)
+		srv := ctx.Value(http.ServerContextKey).(*http.Server) //nolint:forcetypeassert // must exist
 		if err := srv.Shutdown(graceful.GetManager().HammerContext()); err != nil {
 			log.Error("Unable to shutdown the install server! Error: %v", err)
 		}