[Amp story captions] Allow Players to get/set the captions state

[processprocess]

Description

This will likely happen here:

amphtml/extensions/amp-story/1.0/amp-story-viewer-messaging-handler.js

Lines 27 to 64 in 112742b

	/** @enum {!GetStateConfigurationDef} */
	const GET_STATE_CONFIGURATIONS = {
	'CURRENT_PAGE_ID': {
	dataSource: DataSources.STORE_SERVICE,
	property: StateProperty.CURRENT_PAGE_ID,
	},
	'EDUCATION_STATE': {
	dataSource: DataSources.STORE_SERVICE,
	property: StateProperty.EDUCATION_STATE,
	},
	'MUTED_STATE': {
	dataSource: DataSources.STORE_SERVICE,
	property: StateProperty.MUTED_STATE,
	},
	'PAGE_ATTACHMENT_STATE': {
	dataSource: DataSources.STORE_SERVICE,
	property: StateProperty.PAGE_ATTACHMENT_STATE,
	},
	'UI_STATE': {
	dataSource: DataSources.STORE_SERVICE,
	property: StateProperty.UI_STATE,
	},
	'STORY_PROGRESS': {
	dataSource: DataSources.VARIABLE_SERVICE,
	property: AnalyticsVariable.STORY_PROGRESS,
	},
	};
	/** @typedef {{action: !Action, isValueValid: function(*):boolean}} */
	let SetStateConfigurationDef;
	/** @enum {!SetStateConfigurationDef} */
	const SET_STATE_CONFIGURATIONS = {
	'MUTED_STATE': {
	action: Action.TOGGLE_MUTED,
	isValueValid: (value) => typeof value === 'boolean',
	},
	};

.

Blocked by #37884