Use Editor Lite in readonly mode to view blobs

What does this MR do?

Currenly when viewing a blob/file (repository -> file), we use haml-based blob viewers to view the blob/file. This MR is part of a bigger effort to Extend the repository Vue app to also show Blob's through Vue.

In this MR we extend the Simple Viewer component to use Editor Lite to view blobs in preparation for Extending the repository Vue app to also show Blob's through Vue.

MR	status
Add Blob Page to the repository vue app	✅ merged
Add Blob content viewer to the repository app	✅ merged
Use Editor Lite in readonly mode to view blobs	This MR
Render blob viewer Vue app	🚧 Not started

Note: This MR is part of a bigger effort to refactor the refactor the repository browser to one Vue application, see &5531 (closed) for more details.

Changes in this MR are behind the :refactor_blob_viewer feature flag.

Screenshots

No visual changes are expected as the feature is behind a feature flag.

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because the feature is behind a feature flag.
• Code review guidelines
• Merge request performance guidelines

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Related to #323200 (closed)