Show editor context content as JSON for syntax highlighting

[ndoschek]

Feature Description:

Display the editor context in JSON format to enable proper syntax highlighting and improve readability. Currently it is Plain Text by default.
This is particularly useful when inspecting or reviewing the context data variable content, making it easier to identify structure and content.

Steps to reproduce:

1. Go to the AI Chat view input and hit the plus button "Attach elements to context"
2. Select "EditorContext"
3. Observe that the context ist shown as Plain Text by default.