Support reader settings

[ianlin-bbpos]

Summary

Support reader settings

Motivation

Support setting & getting reader settings in the RN SDK.

Testing

• I tested this manually
• I added automated tests

Documentation

Select one:

• I have added relevant documentation for my changes.
• This PR does not result in any developer-facing changes.

[maxa-stripe]

@ianlin-bbpos Thanks for the very quick turnaround on this! I got to playing with the dev app, and it looks & works great on Android. However, on iOS I observed the following behavior:

• When text to speech speakers is already enabled on a reader, loading its settings doesn't show the toggle in its "on" condition.
• When I attempt to enable text to speech speakers on a connected reader, I see the following error:
  

I'm not well versed in React Native, so it's possible that I've missed some required setup step. Does this seem familiar at all?

[ianlin-bbpos]

@maxa-stripe Sorry, this is actually my mistake that should not be put, I forgot to do code debugging on the IOS side before create this PR. Let me commit new code modificatione, thanks for your review.