Log Server messages to VS Code output panel

[VitGottwald]

Description

As a USER, I would like to see the COBOL language server logs in VS Code Output panel.

Acceptance Criteria

1. Language Server logs can be viewed from VS Code Output panel - (command palette -> Output: Focus on Output View).
2. ~/LSPCobol folder is no longer used

Definition of Done

• The story is implemented according to the description.
• Unit testing done (Preferably by TDD approach, coverage should be at least 70%).
• Code review done by at least one other team member.
• Manual testing is done.
• Documentation is added and reviewed (if needed).
• The pull request is approved.
• The story is merged into the development branch.
• Tests are performed on the development branch.

Technical details

The VS Code language client that is used to start the language server captures STDERR messages and automatically shows them in VS Code Output panel (it creates an output channel for the extension automatically).
So it should be sufficient to change the implementation to write logs into STDERR instead of writing them to disk.