feat: update organization resource

[ParthasarathyV]

Proposed changes

Adds SecurityContact field support to the MongoDB::Atlas::Organization CloudFormation resource to enable setting the security contact email address for organizations. This field is updatable.

Type of change:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• If changes include removal or addition of 3rd party GitHub actions, I updated our internal document. Reach out to the APIx Integration slack channel to get access to the internal document.

Manual QA performed:

• cfn invoke for each of CRUDL/cfn test
• Updated resource in example
• Published to AWS private registry
• Used the template in example to create and update a stack in AWS
• Deleted stack to ensure resources are deleted
• Created multiple resources in same stack
• Validated in Atlas UI
• Included screenshots

Required Checklist:

• I have signed the MongoDB CLA
• I have added tests that prove my fix is effective or that my feature works
• I have checked that this change does not generate any credentials and that they are NOT accidentally logged anywhere.
• I have added any necessary documentation (if appropriate)
• I have run make fmt and formatted my code
• For CFN Resources: I have released by changes in the private registry and proved by change works in Atlas

Further comments

• Added SecurityContact field to schema, model struct, and handler mappings
• Updated test inputs (inputs_1_create.json and inputs_1_update.json) to include SecurityContact field
• CFN contract tests passed (8 passed, 4 skipped)
• Successfully deployed and verified in AWS CloudFormation private registry
• Verified SecurityContact field is updatable and persists correctly in Atlas

Screenshots:

[ParthasarathyV]

Organization tests failing issue: CLOUDP-332705

[oarbusi]

LGTM