Misc improvements to handlers and web api

[dluc]

Motivation and Context (Why the change? What's the scenario?)

Simplify some dev scenarios.

High level description (Approach, Design)

• Revisit how handlers are loaded when using MemoryService and MemoryServerless, simplify code and allow to load by type.
• Remove OpenAPI dependency from Core. The library is used only by the Web Service and consumers for the Core package won't need the extra assembly.
• Add shortcuts to Persistent and Volatile simple* configs, e.g.
  • new SimpleFileStorageConfig { StorageType = FileSystemTypes.Disk } => SimpleFileStorageConfig.Persistent
  • new SimpleFileStorageConfig { StorageType = FileSystemTypes.Volatile } => SimpleFileStorageConfig.Volatile
  • same for SimpleVectorDbConfig, SimpleQueuesConfig and SimpleTextDbConfig
• Allow to inject generic filters into the Service WebAPI
• Allow to inject no auth filter into the Service WebAPI
• Update notebooks to latest packages
• Reorganize examples and update docs
• Bump Core version to 0.30