Use BlobHeader vue component for repo files

Issue: #323210 (closed)

MR	Changes
This MR	Name (Copy File Path)
This MR	File Size
!60986 (merged)	Edit Link Button
TBD	Web IDE Link Button
TBD	Edit/Web IDE Consolidated Buttons
!60975 (closed)	Lock
TBD	Replace
TBD	Delete
This MR	Viewer Switcher
This MR	Copy content
This MR	Open Raw link button
This MR	Download link Button

What does this MR do?

This MR updates the Repository Files to use the shared Vue BlobHeader component. There are no UI or functionality changes. This is a bigger effort to convert the entire Repository Files Blob from HAML to Vue (YAY Vue 💚)

Simple View (no view switcher buttons)	Rich View (has view switcher buttons)

🏗 Follow-up MRs

• There is an Uncaught error when the copy button is pressed (also exists in production), here's the follow up issue > #329837 (closed)
• The "Copy file contents" button isn't working, this is because we're using a new monaco editor for our content (which is different than the current editor setup), here's the follow up issue so it works with the monaco editor > #329843 (closed)
• The blob content for rich markdown file is not displaying perfectly (spacing is off), but it will be addressed in a future MR. This MR series is focused on the Blob Header only.

Testing Case

This feature is behind a feature flag, to turn on:

rails c

Feature.enable(: refactor_blob_viewer)

1. Navigate to Repository > Files

Simple Viewer

2. Click on a non-markdown file.

Rich Viewer

2. Click on a markdown file.

Simple	Rich

blob-header-markdown

Screenshots (strongly suggested)

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 _____.
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

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
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #323210 (closed)