refactor: wrap server script in main() to avoid polluting globals
refactor: wrap server script in main() to avoid polluting globals

`server.js` is a script, which means when it's bundled all symbols defined
in the file show up in the root scope as globals.
Wrap them in main() function to avoid polluting the scope.

angular/vscode-ng-language-service,angular/vscode-ng-language-service,angular/vscode-ng-language-service,angular/vscode-ng-language-service