The Asciidoctor VS code extension should not override the built-in HTML5 converter

[ggrossetie]

Description

The Asciidoctor VS code extension should not override the built-in HTML5 converter because other converters might rely on it (namely https://github.com/flobilosaurus/vscode-asciidoc-slides)

To Reproduce

Steps to reproduce the issue:

1. Install both the AsciiDoc and the AsciiDoc Slides extensions
2. Try to show a slide preview

Additional Context

Related issue: asciidoctor/asciidoctor.js#1475

We should not register our custom converter for html5 but rather webview-html5:

asciidoctor-vscode/src/asciidocParser.ts

Line 12 in b7102ea

processor.ConverterFactory.register(new AsciidoctorWebViewConverter(), ['html5'])

And then use the backend option to use our converter.

[flobilosaurus]

Hi @Mogztter, when this extension will bump its used asciidoctor.js version to v2.2.6, the bug in my extension asciidoc slides should be fixed right? Or do i need this change here too?

[ggrossetie]

The bump should be enough but we should still do this change to avoid future issues.