MVVM implementation for Create Organization page (create_organization.dart).

[rutvik11062000]

Is your feature request related to a problem? Please describe.
This is the child issue of #758
To implement MVVM architecture on create_organization.dart file.

Describe the solution you'd like
See #760 for in-depth details about the implementation.
For Sample see the PR changes #759

Additional context
Other things to take into consideration:

1. Make sure all the files that you are either updating or creating must be under 300 lines.
2. If there are multiple same widget with only few modification extract it as a method and give only change variable as a parameter.
3. Make the code as concise as possible.
4. Kindly create the test file if it is not created and write tests.

[rutvik11062000]

@Sagar2366 @palisadoes I would like to work on this.