What does this PR do?

Adds the Klaviyo piece with API Key authentication, 10 actions, and 2 triggers.

Actions:

• Create Profile
• Update Profile
• Find Profile
• Create List
• Find List
• Add Profile to List
• Remove Profile from List
• Subscribe Profile
• Unsubscribe Profile
• Find Tag

Triggers:

• New Profile Created
• Profile Added to List

Explain How the Feature Works

Uses Klaviyo API v2024-10-15 with private API key authentication. All endpoints use the standard Klaviyo JSON:API format.

Relevant User Scenarios

• Email marketers managing subscriber lists
• E-commerce stores syncing customer data with Klaviyo
• Automating profile segmentation and list management

Fixes #8284 /claim #8284