Add AI support to the application

[PeterBlenessy]

Use cases where AI support is useful:

• Use AI to summarize issue comments where many comments exist
• Use AI to generate issues description improvements
• Use AI to suggest acceptance criterias
• Use AI to identify smaller increments (MPVs) for large chunks of work

[PeterBlenessy]

Add support for configuring AI API endpoint. It has to be possible to support locally running AI service with OpenAI compatible API, but also be able to use commercially available AI web services

[PeterBlenessy]

Configuration options

• API endpoint
• API key

[PeterBlenessy]

Create an AI configuration tab in the settings dialog with input fields for the ai config options. These options will be available in the Pinia store and persisted in local storage