Add support for glimmer language highlighting

• Please check this box if this contribution uses AI-generated content (including content generated by GitLab Duo features) as outlined in the GitLab DCO & CLA. As a benefit of being a GitLab Community Contributor, you can request access to GitLab Duo.

What does this MR do and why?

Add support for glimmer language highlighting As discussed in #505458 (closed) and #421133 (closed) we add highlighting by using the respective npm packages for highlight_js.

References

This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

• #421133 (closed)
• https://github.com/NullVoxPopuli/highlightjs-glimmer
• !176131 (diffs)

Support in rouge:

• glimmer: No work done yet

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After
	.glimmer .gjs .gts

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.