Feat(Blob): Add graph render support for Blob Viewer

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What does this MR do and why?

Feat(Blob): Add graph render support for Blob Viewer

Adds a rich view for graph files when the integration is enabled.

Supported extensions:

• mermaid
• plantuml
• pu
• puml
• iuml
• d2
• dot
• gv
• noml
• vg
• vl

Changelog: added

References

• solves #17325 (closed)

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

How to set up and validate locally

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

1. Enable the PlantUML integration (https://docs.gitlab.com/ee/administration/integration/plantuml.html#enable-plantuml-integration)
2. Create a .puml file in a repository with example content from documentation
3. view the file in blob viewer