Fix bug and updated tests for creating a record on tables without a primary key

[Shraeyas]

Technical details

• Added condition to check if a primary key exists on table and updated error message to "You cannot insert into tables without a primary key" and status code to 405 if a user tries to insert a new record.
• Added MethodNotAllowedAPIException error class.
• Updated test coverage for validating record creation on tables without primary key .

Checklist

• My pull request has a descriptive title (not a vague title like Update index.md).
• My pull request targets the develop branch of the repository
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I added tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no
  visible errors.

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