raise chatGPT assistant user experience

[ivy-rew]

next step after the first alpha release; raise usability of the assistant

• [x] progress feedback for long running chat GPT requests...
• [x] trim output to increase accuracy to diff file...
• [ ] preset insert statements depending on the active file-editor (json/jsf/java/...)
• [x] config-vars to configure max-chars and th elike
• ~[ ] config with secrets~
• [x] configurable endpoint URis -> also for testing

market:

• [ ] polish product readme.md
• [x] enrich with demo screenshots

[ivy-rew]

working on the most crucial configs https://github.com/axonivy-market/openai-connector/pull/21

[ivy-rew]

progress https://github.com/axonivy-market/openai-connector/pull/22