[Feature] Add linting of HTML code

[devtobi]

Relevant template

refarch-frontend, refarch-webcomponent

Problem description (optional)

Currently we only lint the <template> parts of Vue SFCs in terms of Vue related mechanisms, but we don't check if the is conform to HTML5 standards by the W3C itself.
Thats why we should include a linting tool to scan the HTML parts of our SFCs.

Desired solution

A npm-based solution to lint HTML files should be selected, properly configured and integrated into the lint script.
This allows us to write more clean, maintainable and accessible HTML code.

Considered alternatives (optional)

No response

Additional context (optional)

No response

No duplicate

• I confirm that this issue is not a duplicate

Code of Conduct

• I agree to follow this project's Code of Conduct

[devtobi]

After a quick research I found the following tools:

• https://html-validate.org (actively maintained on GitLab and configurable via configuration file)
• https://htmlhint.com/docs/user-guide/getting-started (last release in 2022, but pretty popular)
• https://github.com/htmllint/htmllint#readme (last pre-release in 2019, not really popular)

I suggest to take a long at html-validate as it is the most active project and is almost equally popular in terms of npm downloads with htmlhint (see https://www.npmjs.com/package/html-validate and https://www.npmjs.com/package/htmlhint)