Sunsetting CDT Cloud Blueprint and integration in Theia IDE

## Background

Since the latest release of CDT Cloud Blueprint, CDT Cloud-specific functionality is primarily provided through VS Code extensions, with the exception of the examples.

At the same time, Theia IDE already provides strong language support for TypeScript and Java. Adding support for C/C++ to Theia IDE is a natural next step and would allow us to better showcase CDT Cloud-related functionality in a broader, more visible environment.

Instead of continuing CDT Cloud Blueprint as a separate product, we propose to integrate the relevant CDT Cloud functionality directly into Theia IDE.

The goal is to enrich the Theia IDE experience with VS Code extensions developed and/or recommended by the CDT Cloud project, and to make this functionality available to a larger audience through the standard Theia IDE distributions.

## Tasks

- [x] Contribute to Theia IDE to include specific VS Code extensions in all published products
- [x] Contribute to Theia IDE Try online to include (possible more) specific VS Code extensions
- [ ] Optional: Contribute examples mechanism to Theia IDE
- [ ] Update CDT Cloud Website
- [ ] Archive CDT Cloud Blueprint repository
- [ ] Update Eclipse project information

## VS Code extensions

This is the list of currently included VS Code extensions:

- "cdt-gdb-vscode": "2.6.0" (try-online)
- "vscode-builtin-cpp": "1.95.3" (try-online)
- "vscode-clangd": "0.2.0" (try-online)
- "vscode-cmake": "1.21.36" (remove until we have a cmake based example -> follow up)
- "cdtcloud-clangd-contexts": "0.8.0" (remove because this is just a POC)
- "vscode-trace-extension": "0.8.0" (remove until this is works in Try Online -> follow up)