AI Assistant - Call to Action component

@kbn/ai-assistant-cta

This package contains a general "Call to Action" component for the AI Assistant, as well as implementations for known, common use cases:

• AddConnector - A CTA to add a new connector.
• InstallKnowledgeBase - A CTA to install a knowledge base.
• NeedLicenseUpgrade - A CTA to upgrade the license to enable an Assistant.
• NeedTierUpgrade - A CTA to upgrade the tier to enable an Assistant, (e.g. Security in Serverless)
• NoConnectorAccess - A CTA advising a user they do not have the ability to add a connector.
• ReadyToHelp - A CTA to let the user know the Assistant is ready to start conversations.