Add support for .svelte

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Describe the feature

.svelte files containing imports are currently not supported. They look like HTML/Vue files.

Demo

This is what a .svelte file looks like:

<script>
	import CustomButton from './CustomButton.svelte';

	function handleClick() {
		alert('clicked');
	}
</script>

<CustomButton on:click={handleClick}/>

Real-life example: https://github.com/hankxdev/one-click-extensions-manager/blob/918841cbdbca86a88498595e660c122c7cef576b/source/App.svelte

Imports of .svelte files from .js files are already supported: https://github.com/hankxdev/one-click-extensions-manager/blob/918841cbdbca86a88498595e660c122c7cef576b/source/main.js

Additional information

Full docs about the language are here, but it looks like HTML for the most part (imports are found in regular <script> tags). My guess is that the .svelte extension can just be added to https://github.com/OctoLinker/OctoLinker/blob/a139f7f8fbc68b4f439edf12941b93271585b98f/packages/plugin-html/index.js

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:woot: