Add containerization, lcov, fix env, scripts, aliases

[FedokDL]

1. Add containerization. Add .devcontainer.json for VSCode for comfortable development. Nothing else needs to be installed locally, only Docker.
2. Fix type format inside .env.example. Now the scripts are working.
3. Add aliases: @contracts and @tests. Getting rid of the ../../ style.
4. Add lcov to container and plugin for vscode. Using the coverage report is now easier.
5. I think it is highly impractical to store other repositories inside a repository as submodules. As it increases its size a lot, moreover submodules are quite demanding and many times there were errors from the git when trying to install something.
   I removed submodules from the repository and instead added a Makefile, which allows us to install the packages we need with a specific version. This command is already installed in the container, but if someone doesn't want to use it, they can simply copy the command to their personal terminal.

[Arvolear]

LGTM!