Experiment on tree-shaking botframework-directlinejs

Initially, cd component && npm install.

For subsequent runs, npm test.

When importing from the root, it will import botframework-directlinejs, but not using it. This produce almost the same build when compared to import 'botframework-directlinejs'.

When importing from named exports, it will not import botframework-directlinejs at all.

As in the table above, just importing botframework-directlinejs incur costs, even without using it.