Feature/issue 308

[sashapanasiuk5]

GitHub

• Main GitHub ticket
• Related PR on Frontend

Code reviewers

• [ ] @github_username

Second Level Review

• [ ] @github_username

Summary of issue

The lack of validation on the backend side

Summary of change

1. Created validators for all entities
2. Two shared resource were created ( FailedToValidate, FieldNames). They are used to construct generic error messages.
3. Old validation logic was moved from handlers to appropriate validators
4. Old Handlers tests were updated
5. Created unit tests for the validators

Testing approach

ToDo

CHECK LIST

• [ ] СI passed
• [ ] Сode coverage >=95%
• [ ] PR is reviewed manually again (to make sure you have 100% ready code)
• [ ] All reviewers agreed to merge the PR
• [ ] I've checked new feature as logged in and logged out user if needed
• [ ] PR meets all conventions