GitHub Provider: Add resource/fields for Custom Properties

[scottford-io]

Is your feature request related to a problem? Please describe.
GitHub Organizations and Repositories offer the ability to set Custom properties:

Custom properties allow you to decorate your repositories with information such as compliance frameworks, data sensitivity, or project details. Custom properties are private and can only be viewed by people with read permissions to the repository.

https://docs.github.com/en/rest/repos/custom-properties?apiVersion=2022-11-28

Describe the solution you'd like
This feature request is to add new resources to access this data:

• github.organization.customProperties- returns the properties set at the organization level.
• github.repository.customProperties - returns the properties set at the repository level.