Rework Platform Layer

[chr-hertel]

The Platform layer needs a rework to

• more flexible capability handling to use generic models as language or embedding models, see refactor: introduce model capabilities with generic base model instead of interfaces with supportsX methods #305
• enable API contracts that are based on OpenAI but differ in details, see Mistral (feat: add support for mistral #291) and Anthropic (feat: extend Claude support for images and pdf input #298)
• enable different architectures than HTTP but still create synergies between HTTP based Platforms when handling responses
  • streaming
  • error handling

This will create a bunch of PRs sitting on top of each other

1. refactor: introduce model capabilities with generic base model instead of interfaces with supportsX methods #305
2. refactor: switch from JsonSerializable to normalizer #301
3. feat: extend Claude support for images and pdf input #298
4. feat: add support for mistral #291