Adding live chat support on valid amp page

## Describe the new feature or change to an existing feature you'd like to see

Adding a component to support live chat on the page without cusotm JS and keeping page AMP valid.

I have already tried using `amp-script` which is not working

@choumx @kristoferbaxter

## Describe alternatives you've considered

A way we can add live chat support handles just like how `amp-analytics` does with analytics provider. It would be very useful we follow the same approach as analytics and pick most widely used live chat providers.

## Additional context

One possible way I tried was using `amp-analytics` with [Segment](https://segment.com) and then adding [intercom](https://intercom.com) as destination but this approach didnt worked. It was sending events and also data to added google analytics but wasnt adding intercom live chat on the page.

Start by reviewing the existing amp-script and amp-analytics approaches, including the reported Segment and Intercom integration attempt. Define which live chat providers and behavior are in scope before implementation. Done means live chat works without custom JavaScript while the page remains AMP-valid.

Written by the indexing model from the issue text.