Improve project schema repository definition

[arkid15r]

Describe the solution you'd like

• Make sure link attributes have uri format.
• Add corresponding tests for all cases (empty/null/invalid)

[moodyadi2006]

@arkid15r Can you assign this to me?

[samyak003]

@arkid15r can i work on this issue?

[moodyadi2006]

@arkid15r My approach : In schema_validators.py file, I will add a check that if value is none or "" then return False otherwise return True and it will validate... Or do you want me to create some extra tests for validation in project_test.py file? As per my knowledge those tests are enough to check for any null, empty or invalid URI....
Is my approach correct or I have to use more robust checking?

[moodyadi2006]

Although I am merging a PR for this work and just let me know for further changes