* feat: add action enum class to referential actions
* feat: write validation func for action name string
* test: write test for validation referential action
* fix: backend database running for action test
* fix: set the string type of value enum class
* fix: debuging return statement type for validation
* fix: return non empty for empty action
* refactor: change in line return if statement
* fix: add iterate method in read document md
* fix: update foreign key docstring types
* docs: write documention of refernal actions
* docs: complete referential actions descriptions
* refactor: rename and reposition referential action
* refactor: change validate referential action func
* test: add assert check for really deleted rows
* fix: debug error problem in renamed enum class
* fix: apply black formatted codes
* docs: update the document for referential actions
* docs: added note for server default argument
Co-authored-by: collerek <collerek@gmail.com>
