Feature/aws account separation and proliferation

[andreasfrisch]

🌟 Changes:

• Requesting an AWS Account is now a separate process from requesting Kubernetes Namespace
• Users are limited to 10 AWS Accounts and provide a string to indicate 'environment
• When requesting a Kubernetes Namespace the users will provide a name and choose an existing account to link
• A single AWS Account can be used for multiple Kubernetes Namespaces
• Kubernetes IAM role and config storage in SSM works as normal
• Separate events are triggered for the two chains of requests
• The API returns information needed for the frontend to render things nicely

⚠️ Warning:

• Breaks API (we could choose not to, but we need to update the frontend anyway)
• ssu-k8s needs updating too, to handle the new events and use improved internal naming properly

🎶 Notes:

• This should be backwards compliant
• This should be (somewhat) easily supportive of multiple kubernetes clusters in the future