Prepare for the release of the new VS Code extension

Before releasing, we must ensure that everything is ready for users when the new VS Code extension (tools/vscode) gets releases.

Acceptance criteria

• When VS Code can't run ligo lsp, it displays a warning to the user on how to set up LIGO and asks for a specific version.
• Bump to version 0.5.0.
• Test that everything is fine in the build extension.