Add AI variable contribution for last executed terminal command

[Fangoling]

What it does

This PR adds the LastTerminalCommand AI Variable Contribution. It stores the last executed terminal command and its corresponding output.

The last terminal output is extracted by extracting the prompt from the terminal history and collecting lines till the next occurrence of the terminal prompt. This enables accurate extraction of command output pairs from the terminal buffer.

How to test

1. Open a terminal in Theia
2. Execute any command, for example: echo hello world
3. Open the AI Chat view and run the following prompt:

@Universal #lastTerminalCommand Explain this terminal command

Breaking changes

• This PR introduces breaking changes and requires careful review. If yes, the breaking changes section in the changelog has been updated.

Attribution

Contributed under the supervision of @JonasHelming as part of the TUM Bachelor Thesis project "Enhancing Terminal Usability in Modern IDEs through AI-Assisted Interaction".

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines