Deletes extension and old web application (...)

The VSCode4Teaching web application already has the features of the extension, so this commit removes the entire implementation of the extension and the previous web application.
An update of the VSCode4Teaching documentation is pending, which will be done when the implementation of the new web application is finished.

Author: diego-guerrero

.github/workflows/README.md

@@ -1,7 +1,7 @@
 # VSCode4Teaching
 **Developer documentation on the Continuous Integration, Delivery and Deployment (*CI/CD*) system of this project**
 
-This project is configured with a continuous integration, deployment and delivery system through [GitHub Actions](https://github.com/features/actions). This system comprises two *workflows*: one for the extension (file [`extension.ci.yml`](extension.ci.yml)) and one for the server and web application (file [`server.ci.yml`](server.ci.yml)).
+This project is configured with a continuous integration, deployment and delivery system through [GitHub Actions](https://github.com/features/actions). This system includes a single workflow that comprises both server and web application ([`server.ci.yml`](server.ci.yml)).
 
 ### Detailed description of declared jobs
 The aforementioned files define the jobs that will be executed sequentially based on the type of changes registered in the repository. These jobs are: