Create architecture diagram

[alexgeorgousis]

This PR adds a high-level architecture diagram illustrating the KFP Operator managing ML pipelines using Kubernetes Custom Resource Definitions (CRDs) across multiple provider and user namespaces. It demonstrates how the operator interacts with Kubernetes components to orchestrate pipelines in various runtime environments.

The PR also integrates the diagram in a diffable and editable format using draw.io, enabling easy version control and collaboration.

Tasks

• [X] Create high-level architecture diagram
• [x] Figure out how to embed draw.io diagrams so they're diffable and editable (if that's possible)

[edinekj]

• Only drawio diagrams saved as SVG support links, which can be used for better navigation. The team decided to use SVG files.
• Diagrams can be opened in the editor from the browser using the orange icon in the bottom right corner or by using extensions in the IDE.
• We should be able to see visual changes in the diagrams (an example is provided below).
• We were able to enable flow animation styles for connectors. More details: link