Sort users and orgs on explore by recency by default (#24279)

This gives more "freshness" to the explore page. So it's not just the
same X users on the explore page by default, now it matches the same
sort as the repos on the explore page.

---------

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

modules/context/form.go

@@ -65,3 +65,8 @@ func (ctx *Context) FormOptionalBool(key string) util.OptionalBool {
 	v = v || strings.EqualFold(s, "on")
 	return util.OptionalBoolOf(v)
 }
+
+func (ctx *Context) SetFormString(key, value string) {
+	_ = ctx.Req.FormValue(key) // force parse form
+	ctx.Req.Form.Set(key, value)
+}