[T053] Extract shared command infrastructure

[petehauge]

Phase: Phase 7: US5 Extensibility
User Story: US5 - Extensible Command Architecture

Extract shared command infrastructure in src/cli/shared.ts

Common option builders for:

• --resource-group
• --service-name
• --subscription-id
• --verbose
• --otel

Include:

• Shared APIM client factory
• Shared artifact store factory

[petehauge]

We haven't gotten any customer feedback for this (and it's been mostly completed already by Elizabeth's work to make it easy for adding new commands). Closing until we hear customer feedback.