[nbcode] An "Enable preview" code action for relevant compiler message

### Description

When editing a file which uses a preview feature (for example unnamed) classes, the LS reports the compiler message which includes "--enable-preview". Whenever the diagnostic contains such message, the codeAction could return a quick-fix to "Enable Preview".

### Use case/motivation

_No response_

### Related issues

_No response_

### Are you willing to submit a pull request?

No

Start at the language server's codeAction handling for diagnostics and trace how compiler messages containing "--enable-preview" are processed. Determine how a quick-fix can enable preview for the relevant file, then verify that the code action is offered only for matching diagnostics and applies the expected setting.

Written by the indexing model from the issue text.