cpp: remove 'theia-cpp' extension from repository

The commit removes the deprecated `@theia-cpp` extension from the repository (extensions
which contribute language-features are deprecated in the framework in
favor of consuming vscode extensions).

The extension can still be referenced in the repository by viewing the
repository's history.

Signed-off-by: vince-fugnitto <[email protected]>

Author: vince-fugnitto

README.md

@@ -24,7 +24,7 @@ Collection of Theia extensions related to C/C++ development.
 - `@theia/cpp-debug`:
    - Debugging support using `GDB` through the `cdt-gdb-vscode` extension.
    - Memory view (monitor process memory during debug sessions).
-- `@theia/cpp` **deprecated**: 
+- `@theia/cpp` **deprecated** and **removed** ([past sources](https://github.com/eclipse-theia/theia-cpp-extensions/tree/184f7751f13e1ec021ccae3f076915867168d28d/packages/cpp)): 
    - **Deprecated** C/C++ language-features extension.\
    (Language-features should instead be contributed by VS Code extensions).
 

configs/mocha.opts

@@ -1,5 +1,4 @@
 --require ignore-styles
---require monaco-languageclient/lib/register-vscode
 --require reflect-metadata/Reflect
 --reporter spec
 --watch-extensions js