ac-3 : week-5 : Fixed Assignment and slide upload and download by Instructor

[tech-akash]

Issue that this pull request solves

Closes: #1061

Proposed changes

Brief description of what is fixed or changed

Now Instructor can upload ,view and download Assignment and slide provided by him.

Types of changes

Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other (please describe):

Checklist

Put an x in the boxes that apply

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have created new branch for this pull request
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• My changes does not break the current system and it passes all the current test cases.

Screenshots

Please attach the screenshots of the changes made in case of change in user interface

Other information

Any other information that is important to this pull request

[PranshuNayak]

LGTM!

[samay-rgb]

LGTM

[abhishekkumar5606]

LGTM

[PranshuNayak]

@tech-akash please push the migration for db changes.