TL;DR - Add an Open edX Filter for student_view

This PR adds a new extension point for the student_view handler. By triggering an Open edX Filter before rendering the block's student_view we could:

• Modify the template/context being rendered by the student view during runtime -- eg. by using a plugin that extends ORA
• Access the block status for the student

What motivates us to add this filter is this case specifically:
As a professor or student, I want to check my essay with an external service like Turnitin for plagiarism.

More on the filter's definition in this PR: openedx/openedx-filters#107

What changed?

• A new Open edX Filter is triggered before returning the student fragment. When there is no filter configured, this change acts as a noop.
• We added the block object to the context so the filter can access the needed data, which can be a lot when rendering a template. We're open to suggestions on how we can improve it!
• Added openedx-filters to the requirements list

Developer Checklist

• Reviewed the release process
• Translations and JS/SASS compiled
• Bumped version number in openassessment/__init__.py and package.json

Testing Instructions

This is a proof of concept, so testing it can be wacky. Here's a list of steps you can follow so you can test the ongoing implementation:

1. Install the needed libraries:

pip install git+https://github.com/openedx/openedx-filters.git@MJG/ora-student-view-filter
pip install git+https://github.com/eduNEXT/edx-ora2.git@MJG/ora-student-view-filter
pip install git+https://github.com/eduNEXT/platform-plugin-turnitin.git@MJG/turnitin-pipeline-step

2. Add the following configuration:

    OPEN_EDX_FILTERS_CONFIG = {
      "org.openedx.learning.ora.student_view.render.started.v1": {
          "fail_silently": False,
          "pipeline": [
              "platform_plugin_turnitin.extensions.filters.CheckTurnitinForPlagiarism",
          ]
      },
    }

3. Restart services
4. Configure an ORA block for text submissions
5. Submit your assessment

Reviewer Checklist

Collectively, these should be completed by reviewers of this PR:

• I've done a visual code review
• I've tested the new functionality