feat: new JS tutorial from the hands-on

[danil-pavlov]

No description provided.

[koshachy]

Reviewed 525 lines in js-react.md
Will return later.

[github-actions]

This PR is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 7 days.

[github-actions]

This PR is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 7 days.

[AlexanderPrendota]

Bad samples
Snippets:
File: docs/topics/js/js-react.md

import react.dom.*
import kotlinx.browser.document
import kotlinx.css.*
import kotlinx.serialization.Serializable
import styled.*

//sampleStart
fun main() {
   render(document.getElementById("root")) {
      h1 {
         +"Hello, React+Kotlin/JS!"
      }
   }
}
//sampleEnd

(0:7, 0:12) ERROR Unresolved reference: react
(1:15, 1:22) ERROR Unresolved reference: browser
(2:15, 2:18) ERROR Unresolved reference: css
(3:15, 3:28) ERROR Unresolved reference: serialization
(4:7, 4:13) ERROR Unresolved reference: styled
(8:3, 8:9) ERROR Unresolved reference: render
(8:10, 8:18) ERROR Unresolved reference: document
(9:6, 9:8) ERROR Unresolved reference: h1
(10:9, 10:10) ERROR Unresolved reference: +

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[github-actions]

This PR is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 7 days.

[github-actions]

This PR is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 7 days.

[github-actions]

This PR is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 7 days.

[SebastianAigner]

Some improvements here and there still possible, overall looking good!

[SebastianAigner]

Thanks for applying all my feedback! Only some very minor points left.