fix: Revert back to boolean type for experimental-ivy flag
fix: Revert back to boolean type for experimental-ivy flag

This flag was accedentally changed to an array in
440a6c68e93e11d8b6c7f9001b3cb55a5e44dc66
It needs to be only a boolean so that it stays a checkbox in the UI.

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