duplicating middle-high.js to avoid entry point check failures

[annaxuphoto]

To unblock staging, we are duplicating middle-high.js in order to circumvent the following entry point check error:

✘ code.org/public/student/middle-high ➜ ./src/sites/code.org/pages/public/student/middle-high.js
  ✘ Entry points should only be used by one template but this one is used by 2!
  this entry point is referenced by the following templates:
    ../pegasus/sites.v3/code.org/public/student/middle-high-alt.haml
                                 public/student/middle-high.haml

Links

Testing story

Deployment strategy

Follow-up work

Privacy

Security

Caching

PR Checklist:

• Tests provide adequate coverage
• Privacy and Security impacts have been assessed
• Code is well-commented
• New features are translatable or updates will not break translations
• Relevant documentation has been added or updated
• User impact is well-understood and desirable
• Pull Request is labeled appropriately
• Follow-up work items (including potential tech debt) are tracked and linked

[davidsbailey]

Looks good to merge without waiting for drone, to unblock the staging build.