Add SCP for preventing disabling Security Hub and leaving organization setup

[0xjjoyy]

Use Case - Is your feature request related to a problem? Please describe.
A clear and concise description of what the problem is.
Add SCP for preventing disabling Security Hub and leaving organization setup for member accounts in the AWS Organization

Expected Outcome - Describe the solution you'd like
A clear and concise description of what you want to happen.
SCP which prevents securityhub:DisableSecurityHub and securityhub:DissociatefromMasterAccount , attached to the root of the organization

Describe alternatives you've considered
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Affected AWS resource
Mention the AWS resources which is affected
SecurityHub

Impact
High: The issue makes a service level improvement which affects all users of AWS
Medium: Single feature which affects a single functionality which is optionally enabled in the AWS service
Low: Niche use case which is particularly affecting the AWS resources if it is configured in a certain way
Medium

Supported material
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I can contribute: Yes/No
If you are able to contribute towards resolving this request.
Yes

Additional context
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Pull Request number
13

[bksarthak]

#13 ready to merge