[Backend] Implement Single Issues Endpoints (GET, PUT, DELETE)

[vaishnavi-gupta18]

Description

Create following endpoints for Issue : 1) Get a particular issue ( GET - /api/v1/issue/issue_info/<int:project_id>/<int:issue_id>) 2) Update an issue ( PUT - /api/v1/issue/issue_info/<int:project_id>/<int:issue_id>) 3) Delete an issue ( DELETE - /api/v1/issue/issue_info/<int:project_id>/<int:issue_id>) 4) Assign an issue ( PUT - /api/v1/issue/assign/<int:project_id>/<int:issue_id>)

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

How Has This Been Tested?

Test Configuration:

• Ubuntu 20.04
• Postman

https://user-images.githubusercontent.com/76858666/172876762-f717698d-3b9b-4edf-81b3-1c45bbbff88f.mp4

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes
• [ ] Any dependent changes have been merged and published in downstream modules