fix(kotlin): Add ktm and ktx as an alias for Kotlin

[DarkMatter-999]

closes #4318

Changes

Added ktm and ktx as an alias for Kotlin in src/languages/kotlin.js

Testing instruction:

hljs.getLanguage("kts").name;
hljs.getLanguage("ktx").name;
hljs.getLanguage("ktm").name;

<pre><code class="language-kts">
    // Code here.
</code></pre>

<pre><code class="language-ktx">
    // Code here.
</code></pre>

<pre><code class="language-ktm">
    // Code here.
</code></pre>

Checklist

• Added markup tests, or they don't apply here because...
• Updated the changelog at CHANGES.md