Share Button amp-story-player dispatch event click

### Description

I am trying to listen to a share button with a custom event, however, there's no click event associated with it.

### Reproduction Steps

1. Click on the share button
2. Try to use an Custom Event like , navigation, storyNavigation
Example:

document.querySelectorAll('amp-story-player').addEventListener('navigation', (event) => {
console.log('click to share button');
})

### Relevant Logs

_No response_

### Browser(s) Affected

Chrome, Firefox, Safari, Edge, UC Browser

### OS(s) Affected

_No response_

### Device(s) Affected

_No response_

### AMP Version Affected

v0

Start at the amp-story-player entry point and trace how the Share button is handled and which custom events are exposed. Reproduce the issue using the provided navigation and storyNavigation listener example; done means activating Share emits a documented event that listeners can receive across the listed browsers.

Written by the indexing model from the issue text.