Release 0.7.0 with vision capabilities and other tweaks

Adjusts workflow to use new API cache format

Tweaks vision example and README.

Merge pull request #146 from microsoft/copilot/refactor-llm-api-caching

Merge origin/development into copilot/refactor-llm-api-caching

Updates README and improves a community-contributed example.

Adds cache key invalidation mechanism for retry on error

Makes sure the API cache is preserved during test workflows even if some tests fail.

Fixes issues in tests.

Migrate LLM API cache from pickle to JSON format with shared LLMCacheBase class

Initial plan

Tweaks LLM API caching for testing.

Tweaks tests workflows.

Tweaks automated tests and verifications.

Fix typo.