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/web/shared/user/block.go

@@ -66,7 +66,7 @@ func BlockedUsersPost(ctx *context.Context, blocker *user_model.User, redirect s
 		return
 	}
 
-	form := web.GetForm(ctx).(*forms.BlockUserForm)
+	form := web.GetForm[*forms.BlockUserForm](ctx)
 	err := blockedUsersPost(ctx, form, blocker)
 	if err == nil {
 		ctx.JSONRedirect(redirect)