[USH-220] Add Create Post Command

[kubabialy]

Revise the create method for the Post Laravel model to follow CQRS pattern

Description: The create method in the Post Laravel model needs to be revised to follow the CQRS pattern. The logic other than related with HTTP will be moved to the CommandHandler. The aim is to separate the read and write concerns to enhance the codebase's scalability and maintainability.
Tasks:

• Revise the create method to use the CQRS pattern
• Move all the logic other than related with HTTP to the CommandHandler
• Write unit tests to validate the functionality

Acceptance Criteria: The create method should create a new Post instance in the database. The method should utilize the CQRS pattern, and unit tests should pass.

_USH-220