Render snippet blobs

What does this MR do?

Before git version snippets, we stream the data from the database to the user. Now that we have blobs in the repository, we can pass the blob id to Workhorse, and let it do the streaming part.

We need to ensure we still render snippet without repository blobs in the old way, as text.

Closes #212584 (closed)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [ ] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content