Create user

### Feature: Create User
>Create a new user in a database.
#### Pre-requisites:
- [ ] user DAO( create user )
- [ ] user service ( create(User user) )
#### Validations:
- [ ] Form Validation
* create( User user )
* user null
* name ( null, empty, pattern )
* email ( null, empty, pattern )
* password ( null, empty, pattern )
* phone number ( length, >= 600000001 && <= 9999999999 )
- [ ] Business Validation
* Email Already exists
#### Messages:
* Invalid User object
* Invalid name input
* Invalid email input
* Invalid password input
* Invalid phone number input
* User already exists
#### Flow:
```mermaid
graph TD;

A[Value Passed to UserService - User Object] --> B[Form Validation & Business Validation]

B--> C{Validation Result}

C -- Valid --> D[Value Passed to UserDAO]

D --> E[Store Value in Database]

C -- Invalid --> F[Validation Exception]
```

Start at the UserService create(User user) entry point and trace the form and business validation flow to UserDAO and the database. Use the listed validation rules and messages as the acceptance criteria, including rejecting duplicate email addresses and invalid user fields.

Written by the indexing model from the issue text.