Kyoto: Controlling component loading state using ssa:oncall.display attribute

Hello, community! First of all, I'd like to mention that post is related to `kyoto` golang frontend library. You can find this project here: [https://github.com/yuriizinets/kyoto](https://github.com/yuriizinets/kyoto)

Not so long time ago, we've added feature to control UI while making server side action. As far as server side actions are making roundtrip to the server every time an action is triggered, there are cases when the page may not react immediately to a user event (like a click). So, we've provided a way to easily change `display` parameter during action call.

I'll go straight to the demonstration, and then I'll describe in details what's going on. [demo](https://user-images.githubusercontent.com/17050536/140986021-793d3a1e-6e1a-48e0-acc5-82080a4f1376.mp4)

First of all, we're hiding loading element with `style="display: none;"` (or with `hidden` class in case of Tailwind). It could be spinner, progress bar, whatever. Then, we can control this display style while calling an action with `ssa:oncall.display`. Example:

```html <div ssa:oncall.display="block" style="display: none;"> ... </div> ```

Also, don't forget that you can hide certain elements during action call with `ssa:oncall.dispay="none"`.

That's all! On action call ending display attribute will return to the initial state.