Refactor config create command

[UmeshSingla]

Fixes: #94
Fixes #180

Refactored code for wp config create command renders the default moustache template with default values along with the extra-php input if specified. And further it uses update method from WPConfigTransformer class to set the config values for all provided arguments.

[ernilambar]

@UmeshSingla Can you please add tests also? Ref: Functional Tests

[UmeshSingla]

@UmeshSingla Can you please add tests also? Ref: Functional Tests

@ernilambar Aren't the existing tests enough? If not, Could you possibly provide me with an example of changes that can use additional tests.

https://github.com/wp-cli/config-command/blob/main/features/config-create.feature

[ernilambar]

@UmeshSingla Can you please add tests also? Ref: Functional Tests

@ernilambar Aren't the existing tests enough? If not, Could you possibly provide me with an example of changes that can use additional tests.

https://github.com/wp-cli/config-command/blob/main/features/config-create.feature

For refactoring part, current tests are fine. Adding test for this issue #180 would be good.

[UmeshSingla]

@ernilambar I've added functional test for #180. Does this looks ok to you? 0601669