Add getters for anonymousID, attributionID and advertiserID

[VEnom42]

Fixes #599

• Added access to anonymousID, attributionID and advertiserID from native sdks.

Test Plan:

Integrate the sdk to any project and try to get this values:

import {AppEventsLogger} from 'react-native-fbsdk';
...
    AppEventsLogger.getAnonymousID()
      .then(anonymousID => {
        console.log('anonymousID fbsdk', anonymousID);
      })
      .catch(e => {
        console.error(e);
      });
    AppEventsLogger.getAdvertiserID()
      .then(advertiserID => {
        console.log('advertiserID fbsdk', advertiserID);
      })
      .catch(e => {
        console.error(e);
      });
    AppEventsLogger.getAttributionID()
      .then(attributionID => {
        console.log('attributionID fbsdk', attributionID);
      })
      .catch(e => {
        console.error(e);
      });
...

Note that attributionID will be empty on emulators.

[janicduplessis]

I think we can make all the functions not blocking and use the promise API since they are async in JS anyway.

[janicduplessis]

👍 Thanks!